Nail Biopsy: Indications and Methods

Phoebe Rich, MD Oregon Health Sciences University, Portland, Oregon

Nail biopsy is a safe and useful technique for diagnosis and needs to be excellent anesthesia and hemostasis. The type of management of many nail conditions. A basic understanding of nail biopsy depends largely on the location of the pathology in nail anatomy and biology is a prerequisite for a successful nail the nail unit. The techniques of nail biopsy by location in the biopsy. The patient must be adequately prepared and there nail unit and by lesion type are discussed.

THE NAIL BIOPSY is a useful technique for making a ible scar in the nail than a proximal nail matrix biopsy. diagnosis of a clinically ambiguous nail condition that There is no subcutaneous tissue in the nail unit and is not diagnosable by history, clinical appearance, and the periostium lies immediately beneath the nail unit. routine mycology. It can be performed safely, painlessly, Therefore a biopsy of the nail is taken directly down and with a minimum of scarring. Nail biopsy can pre- to bone. The insertion of the extensor tendon is ap- vent serious outcomes in potentially harmful or disfigur- proximately 12 mm proximal to the cuticle. This struc- ing nail conditions. The nail biopsy can be performed by ture is usually proximal in most nail surgeries (Figure 2). a variety of techniques that are outlined in this article. The objectives of a nail biopsy are to obtain a diagnosis of a nail condition in a safe technique without pain Blood Supply and Hemostasis or permanent nail dystrophy.1 The lateral digital arteries are the main blood supply Prerequisites for a successful nail biopsy are the fol- to the nail and course down the sides of the digit. A lowing: complete understanding of nail anatomy and tourniquet is rarely necessary to control bleeding in biology, proper patient selection and preparation, ade- nail surgery, but when one is used, a flat Penrose drain quate anesthesia and hemostasis, proper technique, and or a digital tourniquet is helpful (Figure 3). If a tourni- a nail condition that has eluded diagnosis by simple his- quet is used, it is important that it not be left in place tory, clinical inspection, and routine mycology (Table 1). for more than 15 minutes. Hemostasis is easily achieved The physician performing nail surgery needs a fun- by applying pressure over the lateral digital arteries by damental knowledge of nail unit anatomy, blood sup- gently applying pressure on the sides of the finger dur- ply to the nail and hemostasis, sensory nerves, and an- ing the procedure. esthesia. Anesthesia Anatomy of the Nail Unit Patient acceptance of nail surgery is sometimes hin- A thorough understanding of the anatomy of the nail dered by worry about the pain of the procedure. It is is crucial for a successful nail biopsy procedure. The necessary to have perfect anesthesia and a painless most vital structure in the nail unit is the nail matrix, procedure. Cutaneous sensory nerves run parallel to which is visible as the half moon-shaped structure at the blood vessels down the sides of the digit. Anesthe- the base of the nail. The matrix is the germinative epi- sia can be applied in two locations: digital block and thelium that produces nail plate (Figure 1).2 Damage wing block (Figure 4). A digital block involves injec- to the matrix has the potential to permanently scar the tion of up to 2 cc of plain lidocaine into the lateral nail. It is useful to recognize that the distal matrix forms base of the digit. A paronychial or wing block allows a the inferior part of the nail plate and the proximal ma- smaller volume of anesthetic to be injected into the trix forms the superficial layers of the nail plate. A bi- proximal nail fold and achieves more rapid anesthesia. opsy of the distal matrix is less likely to result in a vis- The small volume of anesthesia in the wing block causes blanching and facilitates hemostasis. P. Rich, MD has indicated no significant interest with commercial A well-prepared patient helps ensure a successful supporters. procedure. A careful history and physical examination Address correspondence and reprint requests to: Phoebe Rich, MD, with a full differential diagnosis is an important starting 2222 NW Lovejoy St., Portland, OR 97210 point. Use of medications such as coumadin and salicy-

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Table 1. Prerequisites for a Successful Nail Biopsy

Understanding of nail anatomy and physiology Proper patient selection and preparation Adequate anesthesia Hemostasis A nail condition that has eluded diagnosis by routine clinical inspection, history, radiologic, and microbiologic techniques A dermatopathologist who is familiar with the histopathologic idiosyncrasies of the nail unit

Figure 3. Marmed digital tourniquet.

Figure 1. The nail unit structures.

Figure 2. Drawing of surgical anatomy of the nail unit. lates and a medical history looking for diabetes, periph- eral vascular disease, connective tissue disease, and prosthetic valves and joints are important. Photographs are usually taken before the procedure. The risk of permanent scarring and the possibility that a diagnosis will not be forthcoming even with an adequate biopsy should be discussed with the patient. Imaging studies, primarily roentgenograms, are often an important pre- Figure 4. Digital and wing block. lude to the surgical procedure. Table 2 outlines the necessary routine preoperative preparation of the patient. struments, however, there are a few specialized instruments (Figure 5). The Freer septum elevator (second from left, Figure 5) is a thin, curved instrument that Instruments has blunt blades on each end. It is useful in avulsing Proper instruments will make any nail biopsy easier. the nail atraumatically and in protecting the matrix in Most of the instruments are standard skin surgery in- nail fold biopsies. (Figures 6 and 7).

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Table 2. Preoperative Examination of the Patient

History Drugs: anticoagulants, allergies Heart valves, artificial joints Diabetes, PVD, connective tissue disease, arthritis, cutaneous disease Clinical examination All 20 nails Mucous membranes Skin and hair Laboratory X-ray Mycology, microbiology PAR Possibility of permanent dystrophy Possibility of no diagnosis Length of time for nail to regrow Figure 6. Poorly performed nail biopsy results in nail dystrophy. Bleeding, infection as with any surgery Photographs agnostic and therapeutic. The effect of a pathologic dis- Types of Nail Apparatus Biopsies by Location order on the nail bed results in several possible features: onycholysis, hyperkeratosis, dyschromia, erosion, and a The nail biopsy affords the clinician the opportunity mass that can distort the normal nail anatomy. Nail bed to diagnose and treat nail disorders. Nail biopsy is a biopsy is useful in distinguishing between several diag- safe and effective procedure when performed carefully noses that have similar clinical appearance (Table 3). and properly (Figure 6). The type of biopsy performed Nail bed biopsy will often remove a lesion in its entirety. depends on two factors: the site of the pathology within Biopsy of the nail bed can be performed with a punch or the nail unit and the risk of permanent scarring from by an elliptical excision. The nail is usually avulsed prior the procedure. The most common techniques are exci- to removing the specimen with a punch, although occa- sion, punch biopsy, and longitudinal nail biopsy. When sionally the punch can be taken through the nail plate us- performing a punch biopsy excision in the nail unit, it ing a larger punch for the plate and a smaller punch for is important to orient the excision properly for the the nail bed specimen. An elliptical excision should be best result (Figures 7–9). An excision in the nail bed is oriented in a longitudinal axis. Defects larger than 3 mm oriented longitudinally and a nail matrix excision is are usually sutured. The nail bed heals without scarring, oriented horizontally. A nail fold biopsy is similar to a although there is occasionally some onycholysis. biopsy elsewhere on the skin. The nail biopsy techniques will be discussed by location in the nail unit.

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

Figure 5. Instruments used in nail surgery. The Freer elevator and the dual action nail nipper are on the left side. Figure 7. Diagram of site and orientation of nail biopsies.

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Figure 9. Lesion of the proximal nail fold.

Nail Fold Biopsy

Figure 8. A) Punch biopsy of the nail through the nail plate. B) A It is safe and easy to perform a nail fold biopsy. Indi- punch biopsy of the nail matrix after nail avulsion. 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 from the nail fold, a Freer elevator is inserted under the nail

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 bed Squamous cell carcinoma, Bowen’s disease Hyperkeratosis, dyschromia, onycholysis, destruction of nail plate Basal cell carcinoma Rare, variable clinical appearance Melanoma Pigmentation of nail bed, erosion, destruction of nail plate, 25% amelanotic Kaposi’s sarcoma Pigmentation, elevation, destruction of the nail plate Metastatic carcinomas Mass, pseudo-clubbing, dystrophy, dusky red color, with or without pain Keratoacanthoma Multiple or solitary, nail plate destruction, mass, erosion, granulation tissue, with or without pain Benign tumors of the nail bed Enchondroma Mass, alteration of nail plate, pain Glomus tumor Spontaneous pain, blue red mass Exostosis Mass, elevation of plate, tender, may see secondary infection Osteochondroma Enlargement of digit, elevation or destruction of the nail plate Pyogenic granuloma Exuberant friable mass, needs to be distinguished from amelanotic melanoma Epidermal cyst Mass, nail plate deformity Fibroma Mass, elevation, distortion of the nail Infectious conditions of the nail bed Onychomycosis Hyperkeratosis, dyschromia, dystrophy, onycholysis is negative Warts Verrucous mass, sometimes painful, nail deformity, destruction, must distinguish from vericous carcinoma, squamous cell carcinoma Subungual (Norwegian) scabies Hyperkeratosis of hyponychium Inflammatory dermatosis involving the nail bed Psoriasis Onycholysis, hyperkeratosis, spliter hemorrhage, oil drop discoloration Lichen planus Violaceous discoloration, atrophy of nail bed; if nail matrix is involved, onychorrhexis, hapalonychia, pterygium Other 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.

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is to confirm or exclude the diagnosis of malignant melanoma in a patient with a pigmented lesion of the nail (Table 4). The nail plate can be avulsed (partial proximal avulsion or total avulsion) or a punch biopsy can be taken through the nail plate. An elliptical excision 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 the nail, a longitudinal nail biopsy can be performed. This technique samples all components of the nail unit in- cluding the nail matrix, nail bed, nail fold, and hy- Figure 10. En bloc excision of a nail fold tumor. Note that the ponychium and yields the best information (Figure 11). Freer elevator is inserted under the nail fold to prevent inadvert- A discussion of nail matrix biopsies should include ent damage of the matrix by the scalpel. a specific reference to the treatment of pigmented bands in the nail and when and how those lesions should be ad- fold to protect the underlying matrix from inadvertent dressed. Longitudinal melanonychia (LM) and mel- damage by the scalpel (Figures 10 and 11A). The nail anonychia striata are the terms used for pigmented bands fold heals beautifully by secondary intention. in the nail plate that are caused by increased melanin content.3,4 Not all pigment in the nail is melanocytic; dematiaceous fungi and hemosiderin from blood un- Nail Matrix Biopsy der the nail are other causes of nail pigmentation (Ta- The most important reason to biopsy the nail matrix ble 5). There are no hard and fast rules when trying to

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

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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 matrix Inflammatory 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. decide whether a pigmented nail requires biopsy. In a recent article, features that are helpful in making a clini- Figure 12. Algorithm for the biopsy of pigmented bands in the cal diagnosis of melanoma of the nail (abbreviated with nail. Courtesy Monica Lawry, CP. the letters A–F) include age of the patient, brown/black and breadth less than 3 mm, change in the band, digit involved, extension of pigment onto the nail folds (Hutch- safe to follow pigmented nail lesions in children, al- inson’s sign), and family history of melanoma and dys- though further long-term study may be warranted.7,8 plastic nevi.5 These clinical guidelines are helpful, but the definitive diagnosis of a suspicious-looking pigmented Conclusion band in the nail requires biopsy. Although there are no definitive rules to follow, an algorithm written by Mon- Nail biopsy is a useful technique that is safe when per- ica Lawry outlines a logical sequence that helps deter- formed properly. It facilitates the diagnosis of ambigu- mine the necessity of a nail biopsy to rule out nail bed ous, potentially serious nail conditions and can re- melanoma (Figure 12).6 There is a great deal of contro- move painful or disfiguring nail lesions. Nail biopsies versy about how longitudinal melanonychia in children are well within the domain of all dermatologists and should be approached. Many authors believe that it is really not much more complicated than routine skin surgery. When surgical anatomy of the nail is under- stood and careful techniques are followed, the success Table 5. Some Nonmelanoma Causes of Pigment in the Nail of the nail biopsy is assured. Apparatus Acknowledgment The figures in this article were repro- Melanin and melanin complexes duced from M. Lawry and P. Rich,6 with permission. Normal variant for skin phototype IV, V, and VIa Hypermealnonsis of the matrix epithelium (melanotic macule equivalent) References Lentiginous melanocytic hyperplasiab Junctional nevusb 1. Rich P. Nail biopsy: indications and methods. J Dermatol Surg On- Compound nevusb col 1992;18:673–82. b 2. Zaias N, Alvarez J. The formation of the primate nail plate: an auto- Bowen’s disease, squamous cell carcinoma, basal cell carcinoma radiographic studying squirrel monkey. J Invest Dermatol 1968;51: Laugier–Hunziker syndrome, Peutz–Jegher syndromea 120–36. Addison’s disease, Cushing syndromea 3. Baran R, Kechijian P. Longitudinal melanonychia (melanonychia Postinflammatory hyperpigmentation (i.e., lichen planus, trauma)c striata): diagnosis and management. J Am Acad Dermatol 1989;21: 1165–75. Drugs (AZT, antimetabolites, antimalarials, minocycline)a 4. Dawber RPR, Colver GB. The spectrum of malignant melanoma of a Heavy metal exposure the nail apparatus. Semin Dermatol 1991;10:82–7. Nonmelanin pigmentation 5. Levit EK, Kagen MH, Scher RK, Grossman M, Altman E. The ABC Dematiaceous fungic rule for clinical detection of subungual melanoma. J Am Acad Der- Bacteria (pseudomonas)c matol 2000;42(2 pt 1):269–74. b 6. Lawry M, Rich P. The nail apparatus: a guide for basic and clinical Hematoma (hemoglobin/hemosiderin) science. Curr Prob Dermatol 1999;11:161–208. 7. Tosti A, Baran R, Piraccini BM, Cameli N, Alessandro P. Nail ma- a Most commonly seen in multiple digits. b Most commonly seen in one digit. c Can be seen in single or multiple digits. Hemoglobin (may not be degraded to hemosid- trix nevi: a clinical and histologic study of twenty-two patients. J Am erin) stains with benzidine or Patent blue V. From Lawry M, Rich P. The nail appara- Acad Dermatol 1996;34:765–71. tus: a guide for basic clinical science. Curr Probl in Dermatol 1999;11:161–208, 8. Leaute-Labreze C, Bioulac-Sage P, Taieb A. Longitudinal melanony- with permission. chia in children. Arch Dermatol 1996;132:167–9.