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Pitfalls in obtaining and interpreting bone marrowaspirates: to err is human

Barbara J Bain, Katharine Bailey

ABSTRACT

Pitfalls relating to bone marrow aspirates and theirinterpretation start even before the aspirate is obtained.There can be failure to perform an aspiration that isclinically indicated or, conversely, an aspiration may bedone that is not actually necessary. Once an aspirate isobtained it may be unhelpful because it is a blood tap orvery dilute, or because of the sampling error that isintrinsic to the procedure. Even if an adequate aspirate isobtained, it may be misinterpreted. Megaloblasticmarrows and childrens marrows with increasedhaematogones or marked reactive changes areparticularly prone to misinterpretation. A constantawareness of potential pitfalls and an assessment of the

aspirate in the appropriate clinical context will help toreduce errors.

INTRODUCTIONBone marrow examination is currently the goldstandard investigation for diagnosing and moni-toring many haematological diseases. It can also beuseful for investigating various non-haematologicalconditions. Combining the bone marrow aspiratewith a trephine biopsy enables the haematologistand pathologist to assess not only fine cytological

detail but also the organisation of the bone marrowand the presence of focal abnormalities. Themarrow aspirate can be rapidly and easily obtained,stained and examined, often providing a reliablediagnosis within a matter of hours. However thereare pitfalls in its interpretation.

A request for a bone marrow examination shouldbe regarded as a request for a consultation, not justfor the performance of a technical procedure. Thehaematologist should not be obtaining and subse-quently interpreting the aspirate in isolation, but inrelation to a detailed clinical history and withknowledge of the findings on physical examinationand of the results of other diagnostic procedures.

Sometimes only an aspiration is performed and theaspirate alone gives all the information that isneeded. More often a trephine biopsy is done at thesame time. It is good practice, and often importantfor drawing the correct conclusions, to interpret thebone marrow aspirate in the light of the trephinebiopsyfindings, and vice versa. Should there be anyapparent inconsistency, review of both is required.Ideally the aspirate and the biopsy sections shouldbe examined by a haematologist/haematopatholo-gist who is trained and experienced in both fields. Ifthis is not possible, both films and sections shouldbe reviewed jointly. In the UK this may be done in

the context of a multidisciplinary cancer meeting,but this venue is not always suitable for a careful

assessment of problem cases and not all patientsrequiring a bone marrow examination have cancer.Pitfalls in obtaining and interpreting a bone

marrow aspirate commence even before the proce-dure is performed. We cannot emphasise toostrongly the importance of the clinical features andthe blood film examination as a preliminary step.The blood film can serve to: (i) reveal the diagnosisand thus obviate a bone marrow examination;(ii) help the assessment of whether a bone marrowexamination is indicated or not; (iii) indicate thepreferred site for the biopsy or sites to be avoided;and (iv) suggest a preliminary diagnosis and thusindicate what extra tests should be done on the

aspirate. The pitfalls related to bone marrow aspi-ration are summarised in box 1. There is often littlepublished evidence relating to these pitfalls, so weshall draw on our own unpublished experience andknowledge of misadventures as well as on whatrelevant literature exists.

BONE MARROW ASPIRATION IS DONE WHEN IT ISNOT NEEDED

An assessment of the history, clinical features andblood film should mean that bone marrow aspira-tion is only performed when it is clinically indi-cated. In general, a bone marrow aspiration should

not be performed on the basis of a single abnormalblood count unless other features strongly supportits validity. We are aware, for example of a bonemarrow aspirate that was performed to investigatepancytopenia that was actually due to a bloodsample being taken from above an intravenousinfusion, and of another that was done to investi-gate neutropenia that was also factitious, thepatient having an inherited myeloperoxidase defi-ciency that led to the neutrophils not being recog-nised by an automated instrument. We are aware ofinstances of malaria being diagnosed from a bonemarrow aspirate1; clinical suspicion and carefulexamination of the peripheral blood should avoid

this. Similarly, we are aware of two cases, one ofwhich has been published,2 in which a bonemarrow aspiration was performed for suspectedautoimmune thrombocytopenic purpura, whencareful examination of a blood film subsequentlyrevealed the MayeHegglin anomaly. It has beensuggested that a bone marrow aspirate should notbe used for the diagnosis of Gaucher disease sincea simple blood test can confirm the diagnosis3;avoiding this unnecessary procedure requires thatthe possibility of this diagnosis has been considered.

In the absence of randomised trials and meta-analyses, clinical guidelines can be helpful in

deciding when a bone marrow examination isindicated. Autoimmune thrombocytopenic purpura

St Marys Hospital, Paddington,London, UK

Correspondence toProfessor Barbara J Bain,Department of Haematology, StMarys Hospital Campus ofImperial College Faculty ofMedicine, St Marys Hospital,Praed Street, London W2 1NY,UK; [email protected]

Accepted 22 December 2010Published Online First4 February 2011

J Clin Pathol 2011;64:373e379. doi:10.1136/jcp.2010.080820 373

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(ITP) and monoclonal gammopathy of undetermined signifi-cance (MGUS) will be taken as examples. American Society ofHematology (ASH) guidelines recommend bone marrow aspi-ration at presentation in children only when atypical featuresare revealed by the clinical history, physical examination, bloodcount or blood film.4 During follow-up, aspiration is advised ifthrombocytopenia persists for more than 6e12 months or ifthere is no response to high dose intravenous immunoglobulin.For adults with suspected ITP, ASH guidelines recommend bonemarrow aspiration only when there are atypical features, whenthe patient is aged over 60 years or when splenectomy is beingconsidered.4 The validity of this approach was supported by tworetrospective analyses of 665 and 836 patients, respectively, agedup to 60 years with suspected ITP whose bone marrows wereexamined. The British Committee for Standards in Haema-tology guidelines are similar but not identical to the ASHguidelines. In the case of children, the British Committee forStandards in Haematology advises aspiration not only when

there are atypical features but also before corticosteroid therapyis given.7 This guidance is based on the fear that acutelymphoblastic leukaemia (ALL) will be missed. We are aware ofoccasional instances, including two published accounts,8 9 ofpatients who have inadvertently been given corticosteroids foran alternative diagnosis without the correct diagnosis of ALLhaving been made, but we are not aware of any well docu-mented instance when this has occurred in a patient withsuspected ITP with no atypical features. A number of large seriesof patients have been reviewed from this point of view. Halperinand Doyle reviewed 127 children with suspected ITP in whoma bone marrow aspirate was performed; atypical features werepresent in all five patients who were found to have ALL.10

Dubansky et al retrospectively reviewed records of 2239 patients

with ALL, only one of whom was found to have presented withisolated thrombocytopenia (otherwise normal blood film,haemoglobin concentration >11 g/dl and white cell count>1.53109/l); however this child had marked hepatosplenome-galy.11 Calpin et al reviewed 484 children who had a bonemarrow aspiration for ITP; three cases of leukaemia were foundamong 152 children with atypical features but none were foundamong the 332 children with no atypical features.12 The avail-able evidence supports the position of the ASH guidelines thatbone marrow aspiration is not indicated at diagnosis in childrenwith suspected acute ITP if clinical and peripheral blood featuresare typical.

Bone marrow aspiration is similarly not necessarily indicated

in MGUS. This is a common condition as people age and it maybe an incidental finding unrelated to clinical features. The

prevalence is 4e5% in people in their 70s13 and 14% over the ageof 90 years.14 It would clearly be inappropriate to consider thatall these individuals require bone marrow aspiration. The UKMyeloma Forum and Nordic Myeloma Study Group haveprepared a joint guideline indicating which patients should bereferred to a consultant haematologist for further investigationand which patients who are referred actually require detailedinvestigation, including bone marrow examination.15 Following

these guidelines will avoid unnecessary marrow examination.

BONE MARROW ASPIRATION IS NOT DONE WHEN IT ISNEEDEDFailure to perform a bone marrow aspiration when indicated isusually the result of inadequate assessment of clinical andperipheral blood features, but sometimes it is due to genuinediagnostic difficulty with the possible benefits of bone marrowexamination not being apparent. There is necessarily littledocumentation of the effect on patient management of failing toperform a bone marrow aspiration when it was indicated.Evidence of delayed diagnosis serves as a surrogate marker.Intravascular large B-cell lymphoma is an example of a condition

that is not infrequently diagnosed only at autopsy because ofthe lack of a clinical suspicion and yet the bone marrow is one ofthe tissues often involved. We have also observed extensiveinvestigation of presumed iron deficiency before an eventualbone marrow aspirate revealed that the correct diagnosis wasanaemia of chronic disease subsequently found to be due toHodgkin lymphoma,16 and misdiagnosis of thrombotic throm-bocytopenic purpura, treated by plasmapheresis, before a bonemarrow aspirate revealed a myelodysplastic syndrome (MDS).17

BONE MARROW ASPIRATION IS DONE ON THE WRONG SITEPrevious tissue damage at the site of the aspiration can poten-tially affect the sample, so it is advisable to ascertain whether

the patient has a past history of fractures or radiotherapy to theintended aspiration site prior to carrying out the procedure.Occasionally history and physical examination will indicate thataspiration should be performed from a particular site because ofthe presence of localised pain or bone tenderness.

THE CLINICAL CONTEXT IS NOT ADEQUATELY ASSESSED ANDTHE CORRECT RANGE OF TESTS IS THEREFORE NOT DONE ONTHE ASPIRATEThe haematologist performing the bone marrow aspirate shouldhave attempted to arrive at a provisional diagnosis or at leasthave a differential diagnosis before the procedure is performed.This will indicate when it is important to use part of the aspi-

rate for culture (eg, for mycobacteria or leishmania), immuno-phenotyping or molecular or cytogenetic analysis. When thediagnostic possibilities are broad, it is useful to place some of theaspirate into preservative-free heparin and rapidly stain andexamine one film to assess whether further tests on the aspirateare indicated.

FALSE NEGATIVE RESULTS ARE OBTAINED ASA CONSEQUENCE OF A SAMPLING ERRORBone marrow aspiration is subject to sampling error. It maytherefore fail to detect an abnormality despite there beingdisease in the bone marrow, or may underestimate the extent ofsuch disease. This is because bone marrow lesions can be focal.

In addition, reactive bone marrowfi

brosis may mean that cellsof interest are absent or under-represented in the aspirate. To

Box 1 Pitfalls in obtaining and interpreting a bone marrow

aspirate

< Bone marrow aspiration is done when it is not needed.< Bone marrow aspiration is not done when it is needed.< Bone marrow aspiration is done on the wrong site.< The clinical context is not adequately assessed and the

correct range of tests is therefore not done on the aspirate.< There is a false negative result as a consequence of

a sampling error.< The aspirate is not interpreted together with the trephine

biopsy sections.< The aspirate is misinterpreted.

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some extent sampling error can be overcome by combiningaspiration with trephine biopsy, which increases the chance ofdetecting focal lesions. Lesions that are typically focal includegranulomas and infiltration by lymphoma (Hodgkin or non-Hodgkin), metastatic tumour or systemic mastocytosis. Forexample, in follicular lymphoma there may be no lymphomacells detectable by either microscopy or immunophenotyping ofthe aspirate and yet there is clear paratrabecular infiltration in

the needle biopsy sections. Similarly, in systemic mastocytosisthere may be only very infrequent mast cells in the aspirate;those present may be largely within the fragments and difficultto visualise, and yet the sections show extensive infiltration.

Although trephine biopsy often overcomes the problem ofsampling error, this is not necessarily so, and sometimesrepeated aspirations are needed. This can be true, for example, inhaemophagocytic lymphohistiocytosis in which an initial non-diagnostic bone marrow aspirate does not exclude the diagnosisand should not delay therapy.18

AN ASPIRATE IS NOT INTERPRETED IN RELATION TOA TREPHINE BIOPSYThe preliminary evaluation of the patient permits an assessmentof whether a trephine biopsy is indicated in addition to anaspiration. An aspirate is superior for the assessment of cyto-logical detail (eg, in megaloblastic anaemia and acute leukaemia,for the detection of ring sideroblasts and for assessment ofgranulocyte dysplasia in MDS) but only a core biopsy permitsassessment of marrow architecture, bone structure and reticulinand collagen deposition. The two procedures are thus comple-mentary. Although a trephine biopsy is usually superior for thedetection of lymphoma, it should be noted that there areinstances when the aspirate will demonstrate lymphomatousinfiltration that is not shown by trephine biopsy. In one series of51 bone marrows of patients with non-Hodgkin lymphoma,

10% showed non-Hodgkin lymphoma in the aspirate which wasnot present in the trephine biopsy sections. A second trephinebiopsy then confirmed these finding in those patients witha positive aspirate.19 Similarly, in neuroblastoma, combininga trephine biopsy with an aspirate will also give a higherdetection rate than either alone.20

A trephine biopsy should always be performed if no marrowcan be aspirated or if the aspirate appears very dilute and lackingin particles. It is also essential when the differential diagnosisincludes aplastic anaemia, lymphoma, metastatic malignancy ora myeloproliferative neoplasm. We consider it is also important toperform a trephine biopsy in suspected multiple myeloma, sinceit is not infrequent for there to be a marked discrepancy betweenthe numbers of plasma cells in the aspirate and in trephine biopsy

sections; sometimes the number of plasma cells in the aspirate isless than 10%. A core biopsy at diagnosis is also important forcomparison with post-treatment specimens when an informativeaspirate may no longer be obtained. The estimated extent of bonemarrow infiltration is significantly higher when based onimmunohistochemistry of trephine biopsy sections than whenbased on aspirates, mainly because infiltration may be focal andreticulin may be increased; estimates from a section also showa closer correlation with prognosis than estimates from an aspi-rate.21 This is not, however, a reason to discount the value of theaspirate since a number of studies have shown myeloma cellmorphology to correlate with prognosis.21e24

A trephine biopsy is generally superior in the investigation of

patients with fever of unknown origin, although some parasitesare easier to recognise in an aspirate. In one series of patients the

aspirate was diagnostic in only 16.5% of patients (mainlypatients with leishmaniasis) compared with the trephine biopsyspecimen in 76%.25

It is our practice to always perform a trephine biopsy whenobtaining an aspirate from an HIV-positive patient since oftenthe aspirate is hypocellular and in addition the biopsy sectionsmay reveal granulomas, lymphomatous infiltration or, rarely,Kaposi sarcoma.

Not only should a trephine biopsy be performed when indi-cated but the aspirate films should be interpreted in conjunctionwith the sections or at least with an acknowledgement thatthese exist. The aspirate will often be reported more speedily sothe final interpretation might include a phrase such as Noinfiltration has been detected. Trephine biopsy report to follow or The aspirate is very dilute. Await results of trephine biopsy.

THE ASPIRATE IS MISINTERPRETEDAn aspirate may be misinterpreted because: (i) it is of poortechnical quality; (ii) the correct stains have not been performed;(iii) features that are present are not noticed; or (iv) abnormal-ities are observed but their significance is not appreciated or the

findings do not trigger the correct supplementary tests.

Problems relating to technical qualityCell morphology can only be properly assessed when the cellsare adequately and evenly separated, the cells are not crushed ordistorted, the sample is sufficiently cellular and containsadequate numbers of particles, and the sample is not clotted orpartly clotted.26A dilute specimen may be the result of takinga large volume of marrow for supplementary tests. This problemcan be avoided by aspirating no more than 0.5 ml into a smallsyringe (eg, a tuberculin syringe) for the preparation offilms andthen attaching a second larger syringe to obtain the specimenneeded for flow cytometry or other tests. If a bone marrow is

likely to be intensely hypercellular, for example in acuteleukaemia, it can be useful to anticoagulate part of the specimenwith EDTA so that it can subsequently be diluted for thepreparation of thinner films. Heparin should not be used as ananticoagulant for this purpose since it alters the staining char-acteristics of the cells. The aspirate must be spread and stainedcorrectly so that the fragments and the trails behind them arestained and can be brought under the objective when the slide isplaced in a secure position on the microscope stage. The aspirateshould be spread towards the area where the label is to be placed;if it is spread in the opposite direction the fragments may onlybe under the objective when the end of the slide is in mid-air andunstable. Worse still, if an automated staining machine is usedthe fragments and parts of the films adjacent to them may be

unstained (figure 1). Wedge-spread films are generally ideal forassessment of cytological detail, but it is also desirable to prepareat least one squash preparation of a fragment. This is particu-larly important in suspected multiple myeloma or systemicmastocytosis when the cells of interest may be trapped withinthe marrow particles. It is important that the films have driedthoroughly before they are fixed and stained or artefacts occurthat can be confused with dysplastic changes (figure 2). Poordrying can inadvertently occur when slides are transported tothe laboratory in air-tight plastic slide holders and are thenimmediatelyfixed. Depending on environmental conditions inthe laboratory, it can take many hours for films to dry. Labora-tories need to develop a suitable staining protocol for bone

marrow specimens. Films may require exposure to the stain forconsiderably longer than is necessary for a peripheral blood film.


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Poor staining can lead to errors of interpretation, an examplebeing that if neutrophil precursors are too pink they can bemisidentified as cells of the eosinophilic lineage. If the staining isparticularly poor, it can become extremely difficult to identifythe cells reliably and pick up any morphological abnormality. Aclotted or partly clotted sample is particularly a problem inhypercoagulable states such as acute promyelocytic leukaemiawhen there may be only a small part of the film that is suitable

for examination. If a sample is found to have clotted entirelybefore spreading it will still be suitable for histological sections,which may permit a diagnosis. If specimens are taken intoEDTA, films should be made promptly since prolonged storageat room temperature can produce changes, for example nuclearlobulation and detached nuclear fragments, that simulatedyserythropoiesis.27

It is necessary to recognise various artefacts in order to avoid

misinterpretation. Metastatic tumour cells may be fragile andtherefore crushed, as may the lymphocytes of chronic lympho-cytic leukaemia, but normal bone marrow cells, particularlyerythroblasts, may also be crushed and may be misinterpreted astumour cells. It is necessary to find intact cells for a correctinterpretation. Because of their size, megakaryocytes areparticularly prone to a crush artefact, which may be misinter-preted as evidence of dysplasia (figure 3).

Correct stains not performedAn iron stain should be performed on the initial diagnosticmarrow from every patient. Generally this should be done ona film that includes particles, but each patient must be assessedindividually. If the diagnosis suspected is acute leukaemia or

MDS, it can be more important to reserve particulate films fora Romanowsky stain. If an iron stain is not done as a normalpart of the routine, it is possible to miss a diagnosis of side-roblastic anaemia. We have observed this occurrence whena blood film was not assessed prior to performing the aspirationand the laboratory protocol did not include a routine iron stain.

The use of cytochemical stains has become much less frequentin recent years. It is important that these are not neglected whentheir use is appropriate, for example when there is not speedyaccess to immunophenotyping. Appropriate cytochemistry canconfirm the presence of Auer rods, aid the recognition of thevariant form of acute promyelocytic leukaemia and help inmaking a distinction between acute monoblastic leukaemia and

large cell lymphoma. The role of cytochemistry in helping thenext generation of haematologists to recognise what they areseeing down the microscope should also not be forgotten.

Features present are not notedIt is important to examine an adequate number offilms and toexamine their edges and tails. Metastatic cancer cells may be

Figure 1 Two bone marrow films showing incorrect spreadingtechnique (left) and correct spreading technique (right). The films havebeen stained on an automated staining machine and ill-positionedfragments in the left-hand film have not been stained. Even had theybeen stained, examination of them would have been difficult.

Figure 2 An erythroblast (centre) showing an apparent irregularity of

the red cell membrane, which is actually an artefact due to inadequatedrying prior to fixation.

Figure 3 A megakaryocyte that appears to be multinucleated;

however, this apparent abnormality is due to crushing of the cell duringspreading, with part of the disrupted nucleus being outside the cell.


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irregularly distributed and not present in all films; they may bepresent mainly in the trails or at the edges, including theadvancing edge of the film. Occasionally at relapse of acuteleukaemia or when acute transformation occurs in chronicmyelogenous leukaemia, blast cells are irregularly distributedand it is necessary to examine the trails behind particles ina number offilms to detect a focal but clinically very significantincrease.

Assessment of the presence or absence of iron and its quan-tification requires assessment of a sufficient number of particles;evaluation of a minimum of seven particles, if necessary in morethan one film, is required.28

Misinterpretation of an adequate aspirateBone marrow films may be well spread, well stained and free ofartefacts and yet they are misinterpreted. There are various wellrecognised recurrent misinterpretations that relate to the diag-nostic process rather than to inadequacies of the specimen.Morphological diagnosis is an exercise in pattern recognition and

yet patterns are not as specific as might be thought.Interpretation of a megaloblastic bone marrow is fraught with

hazards since megaloblastosis may result from a deficiency ofvitamin B12 or folic acid, a haematological neoplasm or theaction of a drug that interferes with DNA synthesis. Misdiag-nosis of a deficiency state as MDS or erythroleukaemia isa particularly serious error. Haematologists have been aware ofthis trap for decades and yet patients are still being started onregular transfusions or referred to leukaemia centres for treat-ment following misdiagnosis. The error may be compounded byimmunophenotyping since megaloblastic proerythroblastssometimes express CD34. Some aspects that can help to preventthese particular misadventures are shown in table 1.

There are other non-neoplastic conditions that can lead toa misdiagnosis of MDS. This can occur in lead poisoning, arsenicpoisoning, thalassaemia intermedia, congenital dysery-

thropoietic anaemia,29

copper deficiency30

and HIV infection.The use of haemopoietic growth factors can cause granulocytedysplasia. Agranular neutrophils and micromegakaryocytes havea high degree of specificity for a haematological neoplasm butdyserythropoiesis, even if severe, is lacking in specificity andcaution must be shown when the diagnosis is based on cyto-penia and erythroid dysplasia alone. Recognition of a diagnosticcategory of idiopathic cytopenia of undetermined significance isuseful in order to avoid drifting into the assumption thata patient has MDS because no other explanation can be foundfor cytopenia and dysplasia. This term was first proposed by theInternational Working Group on Morphology of MDS ata meeting in Lisbon in April 2005,3 1 3 2 and was subsequentlyadopted in the 2008 WHO classification33 and by others. It is

obviously not an actual diagnosis but rather a reminder that thesituation is not clear and should be kept under active review.

The failure to detect tumour cells despite bone marrow infil-tration being present is often due to a sampling error. However itcan also be due to a failure to recognise tumour cells that arepresent. This is particularly a problem with small cell tumours ofchildhood. For example, in one study of children with advancedneuroblastoma, 57 of 61 initial samples contained tumour cells

that were detectable by automated immunocytochemistry onthe slides.34 Of these 57 positive samples, cytology of the filmsgave a 45.6% false negative rate; this was particularly likely whentumour cell numbers were low but some specimens containingup to 10% tumour cells were not recognised.34 Specialised tech-niques such as this, applied to films or to the bone marrowaspirate in suspension, can circumvent this problem.

The bone marrows of children can cause particular diagnosticproblems because of the presence of either reactive lymphocytesor immature lymphoid precursors (haematogones). Haemato-gones are cytologically similar to leukaemic lymphoblasts andtheir presence can lead to a misdiagnosis of ALL or a misdiagnosisof relapse when there is a rebound increase of haematogonesfollowing cessation of therapy.35 Since a proportion of haema-togones express terminal deoxynucleotidyl transferase (TdT)they can also be misinterpreted on flow cytometric immuno-phenotyping; it is important for the immunophenotypinglaboratory to appreciate the spectrum of antigen expression byhaematogones in contrast to the more uniform immunopheno-type of leukaemic lymphoblasts to avoid making this error.

The diagnosis of leishmaniasis on a bone marrow aspirate isdifficult when organisms are infrequent. This may becompounded by striking reactive changes, which can includeeither marked dyserythropoiesis or significant plasmacytosis. Ifthis diagnosis is suspected, the bone marrow should be culturedfor leishmania. Errors are most likely to occur in a non-endemicarea, when the clinical history becomes important. For example,

a patient returning to Japan from India and the USA wasmisdiagnosed as having lymphoma, no leishmania having beendetected in the first two of three bone marrow aspirates, whichinstead showed a remarkable infiltration by monocytes andplasma cells.36 Similarly, three French children have beenreported in whom a misdiagnosis of leishmaniasis as infection-related or familial haemophagocytic syndrome led to treatmentwith corticosteroids and etoposide, in one patient for as long as5 months.37 Misdiagnosis as dyserythropoietic anaemia has alsooccurred.38 Haematologists in northern Europe need to be awarethat HIV-positive patients may present with leishmaniasis evendecades after exposure in the Mediterranean region.

Leishmaniasis is not the only condition that can lead toa striking increase of plasma cells that can suggest MGUS or

Table 1 Practices that are helpful in avoiding the misdiagnosis of megaloblastic anaemia due to a vitamin deficiency as myelodysplastic syndrome orerythroleukaemia

Practice to be followed Features of relevance

Paying careful attention to the clinical history Is the patient a vegan? Has there been a gastrectomy or small bowel resection? Are there features suggestingpernicious anaemia or coeliac disease? Has the patient been prescribed an antifolate drug or had repeatedexposure to nitrous oxide?

Not placing absolute reliance on vitamin assays Serum B12 levels are normal in about 5% of patients with megaloblastic anaemia due to deficiency of this vitamin,and red cell folate may be normal when there is a rapid onset of deficiency.

Paying careful attention to morphological details Marked megaloblastosis with striking dyserythropoiesis is not specific for a deficiency state. However, althoughgiant metamyelocytes and hypersegmented neutrophils can occur in MDS, this is quite uncommon and theirpresence strongly suggests a vitamin deficiency.

Carrying out a therapeutic trial A therapeutic trial of vitamin B12 and folic acid should be considered if the evidence suggesting erythroleukaemiaor MDS is not absolutely conclusive.

MDS, myelodysplastic syndrome.


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multiple myeloma. Rarely, patients with infection or an auto-immune disease have 30e50% plasma cells as a reactive change;this has been observed in Sjgren syndrome,39 syphilis, relapsedacute myeloid leukaemia40 and tuberculosis in an HIV-positivepatient.41 A full assessment of other clinicopathological featuresand assessment of the k:l ratio are needed to make thedistinction.

A diagnosis of Gaucher disease may be suspected in patients

with numerous pseudo-Gaucher cells in the bone marrow. Thisdifficulty is best resolved by an assay of peripheral bloodb glucocerebrosidase activity.

Sometimes systematic errors occur in interpretation, whichare resolved with increasing knowledge. This was so with thediagnosis of malignant histiocytosis. This is now known to bea rare condition, with many of the initial reports actuallyrepresenting a misinterpretation of infection-associated or otherreactive haemophagocytic syndromes.42

Sometimes bone marrow findings do not trigger the rightresponse in the observer. We are aware, for example, of a bonemarrow aspirate in a child that showed marked vacuolation ofhaemopoietic precursors and yet this did not lead to investiga-tion for Pearson syndrome.

FUTURE PITFALLSAn interesting consideration for the future is whether there willbe a time when we stop using microscopes and become relianton digital imaging and computerised interpretation. Certainlythe computer processing power now available is approachingthe point where there could feasibly be the capability to scanbone marrow aspirate slides as a matter of routine.43 Would theuse of digital images be an advantage, permitting collective orexpert interpretation even at a distance, thus avoiding some ofthe interpretation pitfalls which have been discussed in thisarticle, or if coupled with automated interpretation, would itlead to a deskilling of haematologists and thus contribute to

misdiagnoses?

CONCLUSIONSMany of the pitfalls described in this review can be avoided byfull clinical assessment, careful morphological analysis of thebone marrow aspirate, appropriate use of special tests, andassociated examination of a bone marrow trephine biopsyspecimen. However, it is also important to be aware of onesown fallibility and to continue to question a presumptivediagnosis. Almost two millennia before Alexander Pope voicedthe thought To err is human, the same characteristic of Homo

sapiens had been pointed out both by the statesman andphilosopher, Marcus Cicero, and by the Stoic philosopher,

Seneca the Younger. Marcus Tullius Cicero (106e

43 BC) wrote:Cuiusvis hominis est errare, nullius nisi insipientis in erroreperseveraredAnyone can err, but only the fool persists in his

fault. Similarly, Lucius Annaeus Seneca (c. 4 BC e AD 65)wrote: Errare humanum est perseverare diabolicumdTo err ishuman; to persist is of the Devil. Keeping the possibility oferror in mind means that an initial misinterpretation is morelikely to be recognised and corrected.

Competing interests None.

Provenance and peer review Commissioned; not externally peer reviewed.

REFERENCES1. Abdulsalam AH, Sabeeh N, Bain BJ. Immature Plasmodium falciparum

gametocytes in bone marrow. Am J Hematol 2010;85:943.2. Bain BJ, Atra A. Thrombocytopenia. Am J Hematol 2008;83:303.3. Beutler E, Saven A. Misuse of marrow examination in the diagnosis of Gauchers

disease. Blood 1990;76:646e8.4. George JN, Woolf SH, Raskob GE, et al. Idiopathic thrombocytopenic purpura. A

practice guideline developed by explicit methods for the American Society ofHematology. Blood 1996;88:3e40.

5. Westerman DA, Grigg AP. The diagnosis of idiopathic thrombocytopenicpurpura in adults: does bone marrow biopsy have a place? Med J Aust1999;170:216e17.

6. Mak YK, Yu PH, Chan CH, et al. The management of isolated thrombocytopenia inChinese adults: does bone marrow examination have a role at presentation? Clin Lab

Haematol2000;22:355e8.7. British Committee for Standards in Haematology General Haematology Task

Force.Guidelines for the investigation and management of idiopathic

thrombocytopenic purpura in adults, children and in pregnancy. Br J Haematol2003;120:574e96.

8. Reid MM. Bone marrow examination before steroids in thrombocytopenic purpura orarthritis. Acta Paediatr 1992;81:1052e3.

9. Naithani R, Kumar R, Mahapatra M, et al. Is it safe to avoid bone marrowexamination in suspected ITP? Pediatr Hematol Oncol 2007;24:205e7.

10. Halperin DS, Doyle JJ. Is bone marrow examination justified in idiopathicthrombocytopenic purpura? Am J Dis Child 1988;142:508e11.

11. Dubansky AS, Boyett JM, Falletta J, et al. Isolated thrombocytopenia in childrenwith acute lymphoblastic leukemia: a rare event in a Pediatric Oncology Group Study.

Pediatrics1989;84:1068e71.12. Calpin C, Dick P, Poon A, et al. Is Bone Marrow Aspiration Needed in Acute

Childhood Idiopathic Thrombocytopenic Purpura to Rule Out Leukemia? Arch PediatrAdolesc Med 1998;152:345e7.

13. Kyle RA, Rajkumar SV. Monoclonal gammopathy of undetermined significance.Br J Haematol2006;134:573e89.

14. Crawford J, Eye MK, Cohen HJ. Evaluation of monoclonal gammopathies in the

well elderly. Am J Med 1987;82:39e

45.15. Bird J, Behrens J, Westin J, et al. UK Myeloma Forum (UKMF) and Nordic Myeloma

Study Group (NMSG): guidelines for the investigation of newly detected M-proteinsand the management of monoclonal gammopathy of undetermined significance(MGUS). Br J Haematol 2009;147:22e42.

16. Chakravorty S, Johnston R, Coulter C, et al. Teaching cases from the RoyalMarsden and St Marys Hospitals, Case 26: refractory microcytic anaemia.

Leuk Lymphoma 2004;45:1491e2.17. Samson RE, Abdalla DH, Bain BJ. Teaching cases from the Royal Marsden and

St Marys Hospitals. Case 18. Severe anaemia and thrombocytopenia with red cellfragmentation. Leuk Lymphoma 1998;31:433e5.

18. Gupta A, Tyrrell P, Valani R, et al. The role of the initial bone marrow aspirate in thediagnosis of hemophagocytic lymphohistiocytosis. Pediatr Blood Cancer2008;51:402e4.

19. Musolino A, Guazzi A, Nizzoli R, et al. Accuracy and relative value of bone marrowaspiration in the detection of lymphoid infiltration in non-Hodgkin lymphoma. Tumori2010;96:24e7.

20. Aronica PA, Pirrotta VT, Yunis EJ, et al. Detection of neuroblastoma inthe bone marrow: biopsy versus aspiration. J Pediatr Hematol Oncol1998;20:330e4.

21. Stifter S, Babarovic E, Valkovic T, et al. Combined evaluation of bone marrowaspirate and biopsy is superior in the prognosis of multiple myeloma. Diagn Pathol2010;5:30.

22. Greipp PR, Raymond NM, Kyle RA, et al. Multiple myeloma: significance ofplasmablastic morphological classification. Blood 1985;65:305e10.

23. Carter A, Hocherman I, Linn S, et al. Prognostic significance of plasma cellmorphology in multiple myeloma. Cancer 1987;60:1060e5.

24. Goasguen JE, Zandecki M, Mathiot C, et al. Mature plasma cells as indicator ofbetter prognosis in multiple myeloma. New methodology for the assessment ofplasma cell morphology. Leuk Res 1999;23:1133e40.

25. Gupta R, Setia N, Arora P, et al. Hematological profile in pyrexia of unknown origin:role of bone marrow trephine biopsy vis-a-vis aspiration. Hematology2008;13:307e12.

26. Riley RS, Williams D, Ross M, et al. Bone marrow aspirate and biopsy:a pathologists perspective. II. Interpretation of the bone marrow aspirate and biopsy.

J Clin Lab Anal 2009;23:259e

307.27. Wang LJ, Glasser L. Spurious dyserythropoiesis. Am J Clin Pathol 2002;117:57e9.

Take-home message

< Interpreting a bone marrow aspirate is a pattern-recognition

exercise that requires both appreciation of context andassessment in the light of other relevant investigations.

< A bone marrow aspirate may be misleading because ofsampling error or poor technical quality or may bemisinterpreted, through human errors, despite a relevant

abnormality being present.


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28. Hughes DA, Stuart-Smith SE, Bain BJ. How should stainable iron in bone marrowfilms be assessed? J Clin Pathol 2004;57:1038e40.

29. Tso A, Kumaran TO, Bain BJ. Case 41: a misdiagnosis of erythroleukemia. LeukLymphoma 2009;50:1e3.

30. Gregg XT, Reddy V, Prchal JT. Copper deficiency masquerading as myelodysplasticsyndrome. Blood 2002;100:1493e5.

31. Mufti G. Minimal diagnostic criteria in MDS: setting the bar. MDS FoundationSymposium The Puzzle of MDS: How Do the Pieces Fit? Annual Meeting of the

American Society of Hematology, Atlanta, GA, 2005.32. Bain BJ. Problems in the morphological diagnosis of MDS. Satellite Symposium: An

evolution in the Understanding of Myelodysplastic Syndromes. Amsterdam: EuropeanHematology Association Congress, 2006.

33. Brunning RD, Hasserjian RP, Porwit A, et al. Refractory cytopenia with unilineagedysplasia. In: Jaffe ES, Harris NL, Swerdlow SH, eds. World Health OrganizationClassification of Tumours: Pathology and Genetics of Tumours of Haematopoietic and

Lymphoid Tissues. Lyon: IARC Press, 2008:94e5.34. Mehes G, Luegmayr A, Kornmuller R, et al. Detection of disseminated tumor cells in

neuroblastoma: 3 log improvement in sensitivity by automatic immunofluorescenceplus FISH (AIPF) analysis compared with classical bone marrow cytology. Am J

Pathol 2003;163:393e9.

35. Anand M, Thavaraj V. Ensuring correctness of bone marrow reports in infants: roleof the pediatrician. Indian Pediatr 2005;42:834e5.

36. Kawakami A, Fukunaga T, Usui M, et al. Visceral leishmaniasis misdiagnosed asmalignant lymphoma. Intern Med 1996;35:502e6.

37. Gagnaire MH, Galambrun C, Stephan JL. Hemophagocytic syndrome: a misleadingcomplication of visceral leishmaniasis in childrenda series of 12 cases. Pediatrics2000;106:e58.

38. Olivieri O, Gandini G, Baiocco R, et al. Visceral leishmaniasis presenting asdyserythropoiesis associated with increased i-antigenicity of erythrocytes.

Haematologica 1987;72:163e5.39. Tanvetyanon T, Leighton JC. Severe anemia and marrow plasmacytosis as

presentation of Sjogrens syndrome. Am J Hematol 2002;69:233.40. Torlakovic EE, Naresh KN, Brunning RD. Bone Marrow Immunohistochemistry.

Chicago: ASCP Press, 2008:134.41. Bayley J, Pavlu J, Thompson M. Striking bone marrow plasmacytosis in a patient

with sickle cell anaemia. Br J Haematol 2008;144:457.42. Wilson MS, Weiss LM, Gatter KC, et al. Malignant histiocytosis: a reassessment of

cases previously reported in 1975 based on paraffin section immunophenotypingstudies. Cancer 1990;66:530e6.

43. May M. A better lens on disease. Sci Am 2010;302:74e7.

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doi: 10.1136/jcp.2010.0808202011

2011 64: 373-379 originally published online February 4,J Clin PatholBarbara J Bain and Katharine Baileymarrow aspirates: to err is humanPitfalls in obtaining and interpreting bone

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