© 2001 by the American Society for Dermatologic Surgery, Inc. • Published by Blackwell Science, Inc.ISSN: 1076-0512/01/$15.00/0 • Dermatol Surg 2001;27:229–234

Nail Biopsy: Indications and Methods

Phoebe Rich, MD

Oregon Health Sciences University, Portland, Oregon

Nail biopsy is a safe and useful technique for diagnosis andmanagement of many nail conditions. A basic understanding ofnail anatomy and biology is a prerequisite for a successful nailbiopsy. The patient must be adequately prepared and there

needs to be excellent anesthesia and hemostasis. The type ofnail biopsy depends largely on the location of the pathology inthe nail unit. The techniques of nail biopsy by location in thenail unit and by lesion type are discussed.

THE NAIL BIOPSY is a useful technique for making adiagnosis of a clinically ambiguous nail condition thatis not diagnosable by history, clinical appearance, androutine mycology. It can be performed safely, painlessly,and with a minimum of scarring. Nail biopsy can pre-vent serious outcomes in potentially harmful or disfigur-ing nail conditions. The nail biopsy can be performed bya variety of techniques that are outlined in this article.The objectives of a nail biopsy are to obtain a diagno-sis of a nail condition in a safe technique without painor permanent nail dystrophy.

1

Prerequisites for a successful nail biopsy are the fol-lowing: complete understanding of nail anatomy andbiology, proper patient selection and preparation, ade-quate anesthesia and hemostasis, proper technique, anda nail condition that has eluded diagnosis by simple his-tory, clinical inspection, and routine mycology (Table 1).

The physician performing nail surgery needs a fun-damental knowledge of nail unit anatomy, blood sup-ply to the nail and hemostasis, sensory nerves, and an-esthesia.

Anatomy of the Nail Unit

A thorough understanding of the anatomy of the nailis crucial for a successful nail biopsy procedure. Themost vital structure in the nail unit is the nail matrix,which is visible as the half moon-shaped structure atthe base of the nail. The matrix is the germinative epi-thelium that produces nail plate (Figure 1).

2

Damageto the matrix has the potential to permanently scar thenail. It is useful to recognize that the distal matrix formsthe inferior part of the nail plate and the proximal ma-trix forms the superficial layers of the nail plate. A bi-opsy of the distal matrix is less likely to result in a vis-

ible scar in the nail than a proximal nail matrix biopsy.There is no subcutaneous tissue in the nail unit andthe periostium lies immediately beneath the nail unit.Therefore a biopsy of the nail is taken directly downto bone. The insertion of the extensor tendon is ap-proximately 12 mm proximal to the cuticle. This struc-ture is usually proximal in most nail surgeries (Figure 2).

Blood Supply and Hemostasis

The lateral digital arteries are the main blood supplyto the nail and course down the sides of the digit. Atourniquet is rarely necessary to control bleeding innail surgery, but when one is used, a flat Penrose drainor a digital tourniquet is helpful (Figure 3). If a tourni-quet is used, it is important that it not be left in placefor more than 15 minutes. Hemostasis is easily achievedby applying pressure over the lateral digital arteries bygently applying pressure on the sides of the finger dur-ing the procedure.

Anesthesia

Patient acceptance of nail surgery is sometimes hin-dered by worry about the pain of the procedure. It isnecessary to have perfect anesthesia and a painlessprocedure. Cutaneous sensory nerves run parallel tothe blood vessels down the sides of the digit. Anesthe-sia can be applied in two locations: digital block andwing block (Figure 4). A digital block involves injec-tion of up to 2 cc of plain lidocaine into the lateralbase of the digit. A paronychial or wing block allows asmaller volume of anesthetic to be injected into theproximal nail fold and achieves more rapid anesthesia.The small volume of anesthesia in the wing block causesblanching and facilitates hemostasis.

A well-prepared patient helps ensure a successfulprocedure. A careful history and physical examinationwith a full differential diagnosis is an important startingpoint. Use of medications such as coumadin and salicy-

P. Rich, MD has indicated no significant interest with commercialsupporters.Address correspondence and reprint requests to: Phoebe Rich, MD,2222 NW Lovejoy St., Portland, OR 97210

230

rich: nail biopsy

Dermatol Surg 27:3:March 2001

lates and a medical history looking for diabetes, periph-eral vascular disease, connective tissue disease, andprosthetic valves and joints are important. Photographsare usually taken before the procedure. The risk of per-manent scarring and the possibility that a diagnosiswill not be forthcoming even with an adequate biopsyshould be discussed with the patient. Imaging studies,primarily roentgenograms, are often an important pre-lude to the surgical procedure. Table 2 outlines the nec-essary routine preoperative preparation of the patient.

Instruments

Proper instruments will make any nail biopsy easier.Most of the instruments are standard skin surgery in-

struments, however, there are a few specialized instru-ments (Figure 5). The Freer septum elevator (secondfrom left, Figure 5) is a thin, curved instrument thathas blunt blades on each end. It is useful in avulsingthe nail atraumatically and in protecting the matrix innail fold biopsies. (Figures 6 and 7).

Table 1.

Prerequisites for a Successful Nail Biopsy

Understanding of nail anatomy and physiologyProper patient selection and preparationAdequate anesthesiaHemostasisA nail condition that has eluded diagnosis by routine clinical inspection,

history, radiologic, and microbiologic techniquesA dermatopathologist who is familiar with the histopathologic

idiosyncrasies of the nail unit

Figure 1. The nail unit structures.

Figure 2. Drawing of surgical anatomy of the nail unit.

Figure 3. Marmed digital tourniquet.

Figure 4. Digital and wing block.

Dermatol Surg 27:3:March 2001

rich: nail biopsy

231

Types of Nail Apparatus Biopsies by Location

The nail biopsy affords the clinician the opportunityto diagnose and treat nail disorders. Nail biopsy is asafe and effective procedure when performed carefullyand properly (Figure 6). The type of biopsy performeddepends on two factors: the site of the pathology withinthe nail unit and the risk of permanent scarring fromthe procedure. The most common techniques are exci-sion, punch biopsy, and longitudinal nail biopsy. Whenperforming a punch biopsy excision in the nail unit, itis important to orient the excision properly for thebest result (Figures 7–9). An excision in the nail bed isoriented longitudinally and a nail matrix excision isoriented horizontally. A nail fold biopsy is similar to abiopsy elsewhere on the skin. The nail biopsy tech-niques will be discussed by location in the nail unit.

Nail Bed Biopsy

Nail bed biopsy is a simple technique that can be both di-

agnostic and therapeutic. The effect of a pathologic dis-order on the nail bed results in several possible features:onycholysis, hyperkeratosis, dyschromia, erosion, and amass that can distort the normal nail anatomy. Nail bedbiopsy is useful in distinguishing between several diag-noses that have similar clinical appearance (Table 3).Nail bed biopsy will often remove a lesion in its entirety.Biopsy of the nail bed can be performed with a punch orby an elliptical excision. The nail is usually avulsed priorto removing the specimen with a punch, although occa-sionally the punch can be taken through the nail plate us-ing a larger punch for the plate and a smaller punch forthe nail bed specimen. An elliptical excision should beoriented in a longitudinal axis. Defects larger than 3 mmare usually sutured. The nail bed heals without scarring,although there is occasionally some onycholysis.

Table 2.

Preoperative Examination of the Patient

HistoryDrugs: anticoagulants, allergiesHeart valves, artificial jointsDiabetes, PVD, connective tissue disease, arthritis, cutaneous disease

Clinical examinationAll 20 nailsMucous membranesSkin and hair

LaboratoryX-rayMycology, microbiology

PARPossibility of permanent dystrophyPossibility of no diagnosisLength of time for nail to regrowBleeding, infection as with any surgery

Photographs

Figure 5. Instruments used in nail surgery. The Freer elevator andthe dual action nail nipper are on the left side.

Figure 6. Poorly performed nail biopsy results in nail dystrophy.

Figure 7. Diagram of site and orientation of nail biopsies.

232

rich: nail biopsy

Dermatol Surg 27:3:March 2001

Nail Fold Biopsy

It is safe and easy to perform a nail fold biopsy. Indi-cations are similar to a biopsy elsewhere on the skin.A nail fold lesion can be removed with a shave, a punch,or an excision. When the specimen is taken en bloc fromthe nail fold, a Freer elevator is inserted under the nail

Figure 9. Lesion of the proximal nail fold.

Table 3.

Nail Bed Disorders and Their Clinical Features for Which a Biopsy May Facilitate Diagnosis

Diagnosis Clinical Nail Findings

Malignant, premalignant, transitional tumors of the nail bedSquamous cell carcinoma, Bowen’s disease Hyperkeratosis, dyschromia, onycholysis, destruction of nail plateBasal cell carcinoma Rare, variable clinical appearanceMelanoma Pigmentation of nail bed, erosion, destruction of nail plate, 25% amelanoticKaposi’s sarcoma Pigmentation, elevation, destruction of the nail plateMetastatic carcinomas Mass, pseudo-clubbing, dystrophy, dusky red color, with or without painKeratoacanthoma Multiple or solitary, nail plate destruction, mass, erosion, granulation tissue, with or

without painBenign tumors of the nail bed

Enchondroma Mass, alteration of nail plate, painGlomus tumor Spontaneous pain, blue red massExostosis Mass, elevation of plate, tender, may see secondary infectionOsteochondroma Enlargement of digit, elevation or destruction of the nail platePyogenic granuloma Exuberant friable mass, needs to be distinguished from amelanotic melanomaEpidermal cyst Mass, nail plate deformityFibroma Mass, elevation, distortion of the nail

Infectious conditions of the nail bedOnychomycosis Hyperkeratosis, dyschromia, dystrophy, onycholysis is negativeWarts Verrucous mass, sometimes painful, nail deformity, destruction, must distinguish

from vericous carcinoma, squamous cell carcinomaSubungual (Norwegian) scabies Hyperkeratosis of hyponychium

Inflammatory dermatosis involving the nail bedPsoriasis Onycholysis, hyperkeratosis, spliter hemorrhage, oil drop discolorationLichen planus Violaceous discoloration, atrophy of nail bed; if nail matrix is involved,

onychorrhexis, hapalonychia, pterygiumOther nail bed conditions

Hemorrhage, trauma Red/black discoloration under nail plate; persistent or nonmigrating hemorrhage needs to be distinguished from melanoma

From P. Rich Nail biopsy: indications and methods. J Dermatol Surg Oncol 1992;18:673–82, with permission.

Figure 8. A) Punch biopsy of the nail through the nail plate. B) Apunch biopsy of the nail matrix after nail avulsion.

Dermatol Surg 27:3:March 2001

rich: nail biopsy

233

fold to protect the underlying matrix from inadvertentdamage by the scalpel (Figures 10 and 11A). The nailfold heals beautifully by secondary intention.

Nail Matrix Biopsy

The most important reason to biopsy the nail matrix

is to confirm or exclude the diagnosis of malignantmelanoma in a patient with a pigmented lesion of thenail (Table 4). The nail plate can be avulsed (partialproximal avulsion or total avulsion) or a punch biopsycan be taken through the nail plate. An elliptical exci-sion of the nail matrix should be oriented horizontally(transverse) and sutured for optimal cosmetic result.

Longitudinal Nail Excision

For large lesions located in the lateral one-third of thenail, a longitudinal nail biopsy can be performed. Thistechnique samples all components of the nail unit in-cluding the nail matrix, nail bed, nail fold, and hy-ponychium and yields the best information (Figure 11).

A discussion of nail matrix biopsies should includea specific reference to the treatment of pigmented bandsin the nail and when and how those lesions should be ad-dressed. Longitudinal melanonychia (LM) and mel-anonychia striata are the terms used for pigmented bandsin the nail plate that are caused by increased melanincontent.

3,4

Not all pigment in the nail is melanocytic;dematiaceous fungi and hemosiderin from blood un-der the nail are other causes of nail pigmentation (Ta-ble 5). There are no hard and fast rules when trying to

Figure 10. En bloc excision of a nail fold tumor. Note that theFreer elevator is inserted under the nail fold to prevent inadvert-ent damage of the matrix by the scalpel.

Figure 11. Lateral longitudinal excisional biopsy. A) Lateral longitudinal pigmented band in the nail. B) Lateral excision from PNF to hy-ponychium along the lateral nail groove; medial incision through the PNF nail plate and nail bed to the hyponychium. C) Dissection fromperiostium starting distally. D) Dissection from periostium proceeding proximally. E) Careful excision of the lateral matrix is important toprevent spicule formation. F) The final defect. G) Approximation of lateral nail fold by suturing through the nail bed and nail plate. H) Thespecimen is oriented and diagramed for processing and interpretation. I)Wound dressing for nail surgery: antibiotic ointment and a nonadherent dressing. J) A bulky gauze dressing protects the surgery site. K) Lateral longitudinal biopsy: two weeks post surgery.

234

rich: nail biopsy

Dermatol Surg 27:3:March 2001

decide whether a pigmented nail requires biopsy. In arecent article, features that are helpful in making a clini-cal diagnosis of melanoma of the nail (abbreviated withthe letters A–F) include

a

ge of the patient,

b

rown/blackand

b

readth less than 3 mm,

c

hange in the band,

d

igit in-volved,

e

xtension of pigment onto the nail folds (Hutch-inson’s sign), and

f

amily history of melanoma and dys-plastic nevi.

5

These clinical guidelines are helpful, but thedefinitive diagnosis of a suspicious-looking pigmentedband in the nail requires biopsy. Although there are nodefinitive rules to follow, an algorithm written by Mon-ica Lawry outlines a logical sequence that helps deter-mine the necessity of a nail biopsy to rule out nail bedmelanoma (Figure 12).

6

There is a great deal of contro-versy about how longitudinal melanonychia in childrenshould be approached. Many authors believe that it is

safe to follow pigmented nail lesions in children, al-though further long-term study may be warranted.

7,8

Conclusion

Nail biopsy is a useful technique that is safe when per-formed properly. It facilitates the diagnosis of ambigu-ous, potentially serious nail conditions and can re-move painful or disfiguring nail lesions. Nail biopsiesare well within the domain of all dermatologists andreally not much more complicated than routine skinsurgery. When surgical anatomy of the nail is under-stood and careful techniques are followed, the successof the nail biopsy is assured.

Acknowledgment

The figures in this article were repro-duced from M. Lawry and P. Rich,

6

with permission.

References

1. Rich P. Nail biopsy: indications and methods. J Dermatol Surg On-col 1992;18:673–82.

2. Zaias N, Alvarez J. The formation of the primate nail plate: an auto-radiographic studying squirrel monkey. J Invest Dermatol 1968;51:120–36.

3. Baran R, Kechijian P. Longitudinal melanonychia (melanonychiastriata): diagnosis and management. J Am Acad Dermatol 1989;21:1165–75.

4. Dawber RPR, Colver GB. The spectrum of malignant melanoma ofthe nail apparatus. Semin Dermatol 1991;10:82–7.

5. Levit EK, Kagen MH, Scher RK, Grossman M, Altman E. The ABCrule for clinical detection of subungual melanoma. J Am Acad Der-matol 2000;42(2 pt 1):269–74.

6. Lawry M, Rich P. The nail apparatus: a guide for basic and clinicalscience. Curr Prob Dermatol 1999;11:161–208.

7. Tosti A, Baran R, Piraccini BM, Cameli N, Alessandro P. Nail ma-trix nevi: a clinical and histologic study of twenty-two patients. J AmAcad Dermatol 1996;34:765–71.

8. Leaute-Labreze C, Bioulac-Sage P, Taieb A. Longitudinal melanony-chia in children. Arch Dermatol 1996;132:167–9.

Table 4.

Indications for Nail Matrix Biopsy

Solitary, unexplained pigmented band in Caucasians, to confirm or exclude the diagnosis of malignant melanoma. Index of suspicion for malignancy may be raised by a band that is new, widened, very dark, present in an elderly patient, or located on the thumb, index finger, or great toe, or associated with pigmentation of the nail folds (Hutchinson’s sign); however, clinical evaluation alone may be inadequate to determine whether or not a longitudinal pigmented band is benign. If there is any doubt, a biopsy is indicated.

Tumor involving the nail matrixInflammatory dermatologic disorder presenting as a nail plate

abnormality, indicating matrix involvement for example, lichen planus or psoriasis. (The clinical application is primarily as a research tool.)

From P. Rich. Nail Biopsy: indications and methods. J Dermatol Surg Oncol 1992;18:673–82, with permission.

Table 5.

Some Nonmelanoma Causes of Pigment in the Nail Apparatus

Melanin and melanin complexesNormal variant for skin phototype IV, V, and VI

a

Hypermealnonsis of the matrix epithelium (melanotic maculeequivalent)

Lentiginous melanocytic hyperplasia

b

Junctional nevus

b

Compound nevus

b

Bowen’s disease, squamous cell carcinoma, basal cell carcinoma

b

Laugier–Hunziker syndrome, Peutz–Jegher syndrome

a

Addison’s disease, Cushing syndrome

a

Postinflammatory hyperpigmentation (i.e., lichen planus, trauma)

c

Drugs (AZT, antimetabolites, antimalarials, minocycline)

a

Heavy metal exposure

a

Nonmelanin pigmentationDematiaceous fungi

c

Bacteria (pseudomonas)

c

Hematoma (hemoglobin/hemosiderin)

b

a

Most commonly seen in multiple digits.

b

Most commonly seen in one digit.

c

Canbe seen in single or multiple digits. Hemoglobin (may not be degraded to hemosid-erin) stains with benzidine or Patent blue V. From Lawry M, Rich P. The nail appara-tus: a guide for basic clinical science. Curr Probl in Dermatol 1999;11:161–208,with permission.

Figure 12. Algorithm for the biopsy of pigmented bands in thenail. Courtesy Monica Lawry, CP.