Questions 08/29/2012

Questions 08/09/2012Hematology, Oncology, Immunology

Question 1A 25 year-old-man with history of acute myelogenous leukemia (AML) presnets with acute onset generalized weakness. He received his first dose of chemotherapy 3 days before. Which of the following is the most likely abnormality on laboratory analysis?HyperkalemiaHypercalcemiaHypophosphatemiaHyponatremiaHypomagnesemia

Answer 1Tumor lysis syndromeTypically occurs 1-5 days after chemotherapyMost common laboratory abnormalities are hyperkalemia, hyperuricemia, hypophosphatemiaSerious complications include renal insufficiency and dysrhythmiasManagement involves normalization of electrolyte abnormalities, IV fluids, and treatment of renal insufficiency

Most likely diagnosis is tumor lysis syndrome, a constellation of events that results from rapid cellular death due to chemotherapy. Rapidly growing and hematologic malignancies highly responsive to chemotherapy are at highest risk for development of tumor lysis syndrome. Hyperkalemia, hyperuricemia, and hyperphosphatemia are the most common laboratory abnormalities. Hypocalcemia is more common than hypercalcemia. Severe fluctuations in magnesium levels are rare. Renal insufficiency and dysrhythmias are the most serious complications. Management involves normalization of electrolyte abnormalities (especially hyperkalemia), intravenous fluids, and treatment of renal insufficiency. Alkalinization therapy to counteract hyperuricemia is not universally recommended, as it may exacerbate electrolyte abnormalities. Renal failure requiring dialysis is a poor prognostic indicator.3

Question 2A 34-year-old woman has a hemoglobin level of 10.0 g per dL with a low mean corpuscular volume. Which of the following is the most likely cause?Alpha-ThalassemiaBeta-ThalassemiaIron-deficiency anemiaSideroblastic anemiaFolate deficiency

Answer 2Iron-deficiency anemiaMost common cause of all anemias in women of child bearing ageFolate deficiency is associated with macrocytic anemia

Iron-deficiency anemia is the most common cause of all anemias of women of child-bearing age, likely due to menstrual blood loss. Iron-deficiency anemia is the number one cause of microcytic anemia and is characterized by rapid response to oral iron therapy. Both alpha and beta thalassemia cause microcytic anemia, but are far less common than iron-deficiency anemia. Microcytosis is more severe in patients with thalassemia than iron-deficiency anemia. Definitive diagnosis is made by hemoglobin electrophoresis. Sideroblastic anemia is usually found in elderly patients, alcoholics, and in those with lead poisoning. Folate deficiency, although common, causes macrocytic anemia.5

Question 3Which of the following is true regarding the peripheral WBC count?Elevation in the WBC count is specific for an infectious processThe presence of 95% neutrophils is also known as a left shiftExercise can elevate the WBC count to more than 15,000 cells per mm3The degree of leukocytosis distinguishes between viral and bacterial infectionA WBC count > 50,000 cells per mm3 is specific for chronic myeloid leukemia

Answer 3Leukocytosis can be seen in any body stress (pain, exercise, pregnancy)Left shift refers to presence of immature WBC forms such as bands, metamyelocytes, or myelocytesDifferential for extremely elevated WBC count includes leukemias, C. difficile colitis, disseminated candidiasis

The WBC count is a relatively non-specific test that is routinely ordered in the ED. A multitude of physiologic and pathologic states can cause leukocytosis, rendering the test useless in most clinical situations. Any body stress, such as pain, exercise, or pregnancy, can increase the WBC count to 20,000 cells per mm3. An elevated WBC has little specificity for the presence of infection. The presence of 95% neutrophils indicates a neutrophilic predominance, not a left shift. A left shift is said to be present when immature WBC forms such as bands, metamyelocytes, or myelocytes are detected in the circulation. The degree of leukocytosis (and even the differential) cannot accurately distinguish between viral and bacterial infection. Few clinical situations cause an extremely elevated WBC count. Although chronic myeloid leukemia is one of the common causes, other leukemias, the leukomoid reaction, C. difficile colitis, and disseminated candidiasis can all cause a WBC count > 50,000 cells per mm37

Question 4Which of the following is true regarding allergic reactions?Like infants, many adults with food allergies will outgrow their allergies over timePatients allergic to honeybee stings will also have similar reactions to wasp stingsMost adverse drug reactions are allergicOral allergen exposure provokes a stronger anaphylactic response than topical exposureAtopy predisposes patients to develop anaphylaxis

Answer 4Little cross reactivity occurs between Apidae (honeybees, bumblebees) and Vespidae (wasps, yellow jackets, hornets) familiesAtopy refers to genetic predisposition to develop hypersensitivity to environmental allergens as well as anaphylaxis

Although many infants outgrow their allergies to food (e.g., eggs, milk, and soy products), adults do not. Honeybees and wasps are both part of the order Hymenoptera, which is a large order of insects that is characterized by locked pairs of membranous wings. Honeybees and bumblebees are part of the Apidae family, whereas wasps, yellow jackets, and hornets are part of the Vespidae family. Although cross-reactivity is common among members of the vespid family, little-cross reactivity occurs between different families of hymenoptera. Only 5% to 25% of adverse drug reactions are allergic. Topical or parenteral exposure each provokes a more significant anaphylactic response than oral exposure. Atopy refers to the genetic predisposition to develop hypersensitivity to environmental allergens as is characterized by asthma, allergic rhinitis (hay fever), and atopic dermatitis. It also predisposes patients to develop anaphylactic reactions9

Question 5Which of the following is the most common presenting symptom of multiple sclerosis (MS)?Urinary retentionHemiparesis of the upper extremitiesAtaxiaAphasiaEye pain and monocular visual loss

Answer 5Optic neuritisSyndrome of monocular eye pain, decreased color perception, variable visual loss primarily affecting central vision20% of multiple sclerosis patients will present with optic neuritis50% of multiple sclerosis patients will experience optic neuritis at some point in the disease course

Optic neuritis is the most common cranial manifestation of MS, and describes a syndrome of monocular eye pain, decreased color perception, and variable visual loss primarily affecting central vision. However, sensory disturbance, diplopia (internuclear ophthalmoplegia), Lhermittes sign (trunk and limb paresthesias evoked by neck flexion), limb weakness, clumsiness, gait ataxia, and neurogenic bladder and bowel symptoms may also be presenting signs and symptoms. Approximately 20% of patients with MS will present with optic neuritis and 50% of patients with MS will experience optic neuritis at some point in the disease course11

Question 6Which of the following is true regarding patients with temporal (or giant cell) arteritis?The most specific finding is jaw claudicationPermanent visual loss occurs in 50% of patientsTreatment with corticosteroids should be withheld until there is a biopsy-proved diseaseVertigo is the most sensitive clinical findingThe peak age of onset is 40 years

Answer 6Temporal (giant cell arteritis)Rare before 50, incidence peaks in 70sMost sensitive finding is new headacheMost specific finding is jaw claudicationPermanent visual loss occurs in 15% of patientsSteroids are the treatment of choice and do not affect biopsy results if performed within a few weeks

Temporal arteritis (or giant cell arteritis) is a large vessel vasculitis that primarily affects branches of the carotid artery. The disease is rare before the age of 50, and incidence peaks in the seventh decade. The most sensitive finding is a new headache, whereas the most specific finding is jaw claudication. However, the disease often presents vaguely with systemic symptoms such as fever of unknown origin, fatigue, malaise, and anorexia. The diagnosis should be considered in any older person with fever of unknown origin. Scalp pain is a more specific finding than headache, particularly when localized over the temporal artery. Vertigo is not a manifestation of the disease. Permanent visual loss occurs in only 15% of patients and is usually preceded by the development of blurring, diplopia, or amaurosis fugax. Corticosteroids are the treatment of choice and should never be withheld if the diagnosis is seriously considered. Multiple studies have demonstrated treatment with steroids does not affect the accuracy of biopsy if performed within a few weeks13

Question 7Which of the following is true regarding idiopathic thrombocytopenic purpura?Five-year mortality is 50%Aspirin is the treatment of choice in adultsTreatment in children is usually supportiveThere is a male predominance in adultsPlatelet therapy is indicated in patients with < 50,000 cells per mm3

Answer 7Idiopathic thrombocytopenic purpura (ITP)Immune mediated destruction of plateletsAcute form in children, chronic form in adults.Most common clinical finding is bleeding.Most common cause of death is intracranial bleeding.Aspirin is contraindicatedSupportive care in children (spontaneous resolution)High dose steroids and/or IVIG in adultsTransfusion is not indicated until platelets reach < 10,000-20,000 cells per mm3

Idiopathic thrombocytopenic purpura (ITP) causes immune-mediated destruction of platelets. Acute ITP is more often seen in children and chronic ITP is seen in adults. Bleeding is the most common clinical finding and intracranial bleeding is the most common cause of death. Treatment in children is primarily supportive with a high rate of spontaneous resolution. Mortality in young adults and children is below 5%; in older adults, it jumps to almost 50% because of complications surrounding intracranial hemorrhage. Aspirin is contraindicated because of its irreversible platelet-killing effects. There is a female predominance in adult patients. Platelets are not indicated until levels reach < 10,000 to 20,000 cells per mm3. Treatment in adults is with high dose corticosteroids and/or IVIG.15

Question 8The most common cause of distal symmetric polyneuropathy isAmyotrophic lateral sclerosisGuillain-Barre syndromeAlcoholismDiabetes mellitusParaneoplastic syndrome

Answer 8Distal neuropathy typically positive (burning, tingling) rather than negative (numbness)Symptoms begin distally and progress proximally

Initial symptoms are typically positive, such as tingling or burning rather than negative, such as numbness. The symptoms begin distally and progress more proximally and affect the lower extremities more than the upper extremities. Over time, weakness develops usually involving dorsiflexion of the big toe followed by weakness of foot dorsiflexion, foot drop, loss of ankle jerks, and finally a steppage gait.17

Question 9A 45-year-old woman is referred to the ED from an optometrist with a diagnosis of bilateral papilledema and rule out pseudotumor cerebri. Which of the following is true about pseudotumor cerebri (also known as idiopathic intracranial hypertension)?Blurry vision is the most common presenting complaintCT scanning will demonstrate hydrocephalus in 80% of casesOculomotor nerve palsy is the most common associated cranial nerve palsyMen outnumber women 4:1Headaches associated with the disorder are usually worse in the recumbent position

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Answer 9Peudotumor cerebri (idiopathic intracranial hypertension)Increased intracranial pressure without identifiable cause. Most common presenting symptom is headache, worse with recumbency and in the morningCT never has hydrocephalusWoman more commonly affected than men

Pseudotumor cerebri, also known as idiopathic intracranial hypertension, is a syndrome of increased intracranial pressure (ICP) without an identifiable cause. To satisfy the diagnostic criteria for the disease, there can be no evidence of a mass, or a structural or vascular lesion on neuroimaging. Furthermore, the composition of the cerebrospinal fluid (CSF) must be normal, and any symptoms resulting from the disease must be completely attributable to papilledema or generalized elevated ICP. The most common presenting symptom is headache, which tends to be worse in the recumbent position and in the morning (after prolong recumbency overnight). CT scan never reveals hydrocephalus. Abducens nerve palsy is the only cranial nerve palsy that commonly occurs and typically presents as intermittent or constant lateral binocular diplopaia. Women are the most commonly affected, with a 19 times increased incidence in obese women of childbearing age.19

Question 10The most common cause of intracranial tumor isMeningiomaAstrocytomaMedulloblastomaMetastasesPituitary adenoma

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Answer 10Most common cause of brain metastasis is lung cancer follow by breast and colon carcinoma

The American Cancer Society estimates that approximately 17,000 people were diagnosed with primary brain tumors in 1999 versus > 100,000 people who died with metastatic brain tumors. The most common cause is lung cancer followed by breast carcinoma and colon carcinoma. Malignant melanoma and renal carcinomas metastasize to the brain less commonly. The malignant gliomas, anaplastic astrocytoma, and glioblastoma multiforme are the most common glial tumors and are typically located in the cerebral hemispheres.21

Question 11Which of the following is the most common cause of large bowel obstruction?MalignancySigmoid volvulusAdhesionsDiverticular diseaseFecal impaction

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Answer 11Malignant neoplasms account for more than half of all casesSecond most common cause is due to volvulusThird most common cause is due to diverticulitis

Malignant neoplasms account for more than half of all cases of large bowel obstruction. Volvulus and diverticulitis (either through stricture, abscess, or phlegmon formation) are the second and third most common causes23

Question 12Which of the following is true regarding lumbar puncture in patients with Guillain-Barre syndrome (GBS)?Campylobacter jejuni can often be visualized in the cerebrospinal fluid (CSF) of pateints with GBSThe classic CSF finding is an elevated protein level with a normal number of white blood cellsLumbar puncture is necessary to make a diagnosis of GBSLumbar puncture is contraindicated in the acute phase of GBS due to elevated intracranial pressure (ICP)The finding of oligoclonal bands is pathognomonic of GBS

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Answer 12Guillain BarreCytoalbumin dissociation refers to the fact that protein levels are elevated without a concomitant rise in WBCTwo requirements for diagnosis of GBS include motor weakness of more than one limb and areflexia (typically global)Oligoclonal bands are most commonly associated with multiple sclerosis

The classic CSF finding in patients with Guillain Barre Syndrome (GBS) is termed cytoalbumin dissociation, which refers to the fact that protein levels are elevated without a concomitant rise in white blood cell counts. Despite this, lumbar puncture and CSF examination is not necessary to make a diagnosis of GBS, although they are usually performed. The only two requirements for the diagnosis of GBS are progressive motor weakness of more than one limb and areflexia, which is typically global. Lumbar puncture is not contraindicated in the setting of GBS. In contrast, it is commonly performed to support the diagnosis and to rule out other causes. Oligoclonal bands are most commonly associated with multiple sclerosis, although they may be present in other diseases as well. They are not found in GBS.25

Question 13A 35-year-old man with history of sickle cell disease presents with acute onset of fever, malaise, fatigue, and lightheadedness. Physical exam demonstrates a tachycardic patient with pale conjunctivae. You suspect aplastic crisis and draw a complete blood count with reticulocyte count. You review his old records and nose that the patients baseline hemoglobin level is 8 g per dL. Which of the following laboratory abnormalities is most consistent with an aplastic crisis?Hemoglobin 8 g per dL, reticulocyte count 6%Hemoglobin 8 g per dL, reticulocyte count 1%Hemoglobin 6 g per dL, reticulocyte count 6%Hemoglobin 6 g per dL, reticulocyte count 1%Hemoglobin 4 g per dL, reticulocyte count 6%

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Answer 13Aplastic crisesCharacterized by worsening anemia (drop of hemoglobin from stable levels) and inadequate reticulocyte response (> 2%)Usually post-infectiousResponsible for 5% of all deaths in sickle cell patients

Sickle cell disease is a hemoglobinopathy causing sickling of red blood cells with any systemic crisis, which results in diffuse microinfarctions. Sickle cell trait is present in approximately 10% of all African Americans, and sickle cell disease is primarily a disease of this population. Symptoms involve multiple organ systems and result in specific acute crises vaso-occlusive, acute chest syndrome, splenic sequestration, and aplastic. Aplastic crises are characterized by the acute onset of worsening anemia combined with bone marrow failure. Laboratory abnormalities demonstrate a drop of hemoglobin of 2 g per dL from stable levels and an inadequate reticulocyte response (< 2%) from the bone marrow to this sudden anemia. Aplastic crises are usually post-infectious and are responsible for 5% of all deaths in sickle cell patients.27

Question 14Which of the following is true regarding anaphylaxis?Bee stings are the most common causeExercise may trigger anaphylaxisAnaphylaxis usually occurs upon first exposure to an allergenAnaphylaxis is a type IV hypersensitivity reactionThe risk of anaphylaxis is greatest in the very young and elderly

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Answer 14AnaphylaxisType I hypersensitivity mediated by IgERequire prior sensitization (as opposed to anaphylactoid reactions)

Foods are the single most common cause of anaphylaxis although up to one third of causes are unknown. Exercise accounts for 7% of anaphylaxis cases. Anaphylaxis occurs as an immediate type I hypersensitivity reaction mediated by immunoglobulin E (IgE) antibodies. It requires prior sensitization to the allergen in order to develop allergen-specific IgE antibodies. Subsequent exposure to the allergen allows mast cell and basophil degranulation leading to the subsequent anaphylactic response. Anaphylactoid reactions are immediate type I hypersensitivity reactions that do not require prior allergen sensitization and which clinically mimic anaphylaxis. Anaphylactoid reactions (e.g. response to iodinated radiographic contrast material) typically require a larger dose of the offending agent but the clinical management is identical to anaphylaxis. Patients at the extremes of age are less likely to have anaphylaxis, probably because of less mature immune response29

Question 15The treatment of Kawasaki Syndrome is intended to prevent: Coronary artery aneurysmsFistula formation from the draining lymph nodesFulminant liver failureMeningoencephalitisParaplegia or quadriplegia

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Answer 15Kawasaki DiseaseAutoimmune disease of blood vesselsCriteria for diagnosis Erythema/cracking of lips or oral cavityRash on the trunkSwelling or erythema of the hands or feetRed eyes (conjunctival injection)Swollen lymph node in the neckTreatment is IVIG and aspirin

The treatment of Kawasaki syndrome is directed toward the amelioration of symptoms and the prevention of coronary aneurysms. Gamma-globulin 2 g/kg intravenously should be administered over 12 hours, followed by high-dose aspirin therapy (100 mg/kg/24 h PO given in divided doses every 6 hours for 14 days). Low-dose aspirin therapy (35 mg/kg/24 h PO) should continue until acute phase reactants return to normal over 35 months. A pediatric cardiologist should follow children to monitor cardiac status. 31