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Anais Brasileiros de Dermatologia

Print version ISSN 0365-0596On-line version ISSN 1806-4841

An. Bras. Dermatol. vol.79 no.5 Rio de Janeiro Sept./Oct. 2004 



Nail apparatus melanoma*



Ignez Regina dos Santos Muri MendonçaI; Bernard Kawa KacII; Renata Teixeira da SilvaIII; Letícia Pereira SpinelliIII; Renata Rodrigues OrofinoIII; Janine Ribeiro FrançaIII

IDermatology specialist. Head of the Santa Casa Dermatology Institute nail Study Center, Rio de Janeiro state
IIHead of the histopathology sector of the Santa Casa Dermatology institute, Rio de Janeiro state
IIIStudents of the Postgraduate program in Dermatology





Nail apparatus melanoma is a rare presentation of melanoma and may be misdiagnosed as junctional nevus, subungual hematoma or onychomycosis. This fact often leads initially to inappropriate treatment and significant delays in appropriately managing such an aggressive disease. The authors report a case of melanoma on the left thumb of a black patient evolving for a year. Emphasis was placed on the importance of assessing certain clinical characteristics in order to reach an early diagnosis.

Key words: nail diseases; melanoma; neoplasms.




Nail Apparatus Melanoma (NAM) is a rare presentation of this neoplasm. It is considered a variant of acral lentiginous melanoma. Its incidence is estimated to vary from 0.7% to 3.5% of all cases of melanoma.1 It is frequently diagnosed in aged patients between the fifth and seventh decade of life, and no predilection for sex has been noticed. It is common among black and Asian persons. Nonetheless, many authors prefer not to associate the epidemiology of the tumor in this topography with race, skin type or sun exposure.1 Pain and discomfort seldom occur as symptoms. A deformation of the ungual blade may be noticed when originating in the nail bed. However, most cases arise gradually in the form of a pigmented lesion on the thumb or the hallux (great toe).2 The most common clinical presentation is a brown or black macule of short duration. Amelanotic forms might be mistaken for pyogenic granuloma. Onychomycosis, subungual hematoma, striated melanonychia and junctional nevus might simulate NAM and must be included in the differential diagnosis.3 The spread of the melanoma pigment into the proximal and lateral edges of the blade (Hutchinson's sign) is indicative of the advanced stage of the disease.1,13 In addition to the clinical diagnosis, which is often assisted by dermatoscopy, the histopathological analysis is of capital importance for the diagnosis. Treatment depends on staging, and surgery is a frequent option. The prognosis is subject to a reservation owing to the disease's aggressive behavior and, above all, a delayed diagnosis in most cases.4



The report discusses the case of a 65-year-old black female patient. A year after experiencing trauma on the left thumb, the patient noticed a dark lesion close to the cuticle extending to the ungual, asymptomatic blade. The patient had no previous alterations on the fingernail. The examination of the finger demonstrated a clear case of melanonychia virtually occupying the entire surface of the ungual blade, distal onycholysis, and median nail dystrophy with a distal fracture of the ungual blade, in addition to periungual pigmentation (Figures 1, 2 and 3). The patient presented with left axillary lymphadenomegaly that was mobile and painless, roughly measuring 1.5 cm. The clinical diagnosis was melanoma. The patient was referred for an incisional biopsy. Histopathology exposed atypical melanocytes infiltrating the reticular dermis, with oval hyperchromatic nuclei, and accentuated cytoplasmic melanin pigmentation (Figures 4 and 5) in addition to an infiltration of the blade itself and the surrounding epidermis. The distal phalanx was amputated and the axillary ganglions removed. It was carried out at the oncology service, which also took charge of following up the case.












NAM was first described by Boyer in 1834,5 and in English by Hutchinson in 1886.6

It is estimated that there is a 2-3% variation in melanomas localized on the nail apparatus in whites and 15-20% in black persons. Nevertheless, there is no significant difference in the number of cases of nail melanoma between white and black persons.7 Incidence in children is rare despite the increase in the overall number of melanoma cases.8

This disease must be suspected anytime a (brown or black) hyperchromic macule appears on the nail matrix, bed or blade. Also suggestive of melanoma is a black longitudinal streak of short duration in white persons, and a clinical change of a preexisting lesion. The spread of the melanin pigment is always suggestive of a tumor. The literature refers to how individuals casually perceive the appearance of a previously inexistent melanocytic lesion, with only two-thirds of patients seeking medical care as a result.7 A biopsy is recommended for every longitudinal melanonychia acquired after puberty in fair-skinned individuals or in the presence of longitudinal melanonychia showing rapid and progressive growth.7,9

Congenital or acquired melanocytic nevi may stem from the nail matrix and clinically present as a longitudinal melanonychia. They are rare and usually of the junctional type. The histopathologic architecture is similar to a nevus localized on the skin. Simple nevic cells may be found in the basal and supra basal layers of the onychocytes. Dendritic melanocytes are only present occasionally on the ungual matrix. Benign melanocytic hyperplasia, which is characterized by an increase in the number of melanocytes among the keratinocytes of the matrix without forming nests, will have to be equally distinguished from nevus and NAM, which is at times difficult. Suspected cases of longitudinal melanonychia must be completely excised and analyzed from a histopathologic and immunohistochemical point of view. The frequency of a nevus-to-melanoma progression of the nail apparatus is not known. The literature informs us that it may disappear spontaneously.7 Dermatoscopy might assist the differential diagnosis of the melanocytic lesions.10

Occasionally, a subungual hematoma might require a differential diagnosis with melanoma. The bluish-red color, lesion irregularity and absence of pigment on the blade point to hematoma. Moreover, the blood stored between the ungual blade and bed is displaced toward the front as the appendage grows. In addition, subungual hemoglobin is not degraded in hemosiderin by the macrophage. Staining with Prussia blue favors a diagnosis of hematoma. However, the difference between hemosiderin and melanin pigment in histopathology sometimes requires an ultra-structural analysis: iron is intercellular whereas melanin is intracellular.7 In dermatoscopy the formation of pseudopods is usually the outcome of erythrocytes penetrating into the layers of the ungual blade. They can act as criteria to distinguish a hematoma from melanoma.

Agents such as Candida guilliermondii, Trichophyton rubrum nigricans, Scytalidium sp, Trichosporum beigelli, among others, might cause melanonychia. The clinical suspicion of mycosis, in association with the positive mycological examinations and histopathology, are decisive for clarifying the diagnosis.

Unlike cutaneous melanoma in which 80% of cases are MNT-1,11 only 20% of NAM cases are at stage I of MNT (a classification for the primary tumor, regional lymphnodes and metastases) at the moment of diagnosis. In an attempt to reverse this situation, Levit and col.11 11 idealized an easy-to-memorize application system. A few characteristics were grouped together according to the letters of the alphabet and designated as the ABC of NAM:
A (age) - Incidence peak between the fifth and seventh decade of life:
B (nail band) - Examine the streak: color usually brown or black, breath and border. The presence of color variations, breath greater than 3 mm, or an irregular border should increase the suspicion of melanoma;
C (change) - Speed and recent increase in size of the streak, compatible with the phase of radial growth, or change in morphology of the nail suggest malignity;
D (digit involved) - The most common sites to be affected, in order of frequency, are assumed to be the thumb, then the hallux and index, and the dominant hand. A pigmented streak on one digit is more indicative of a tumor than its presence on several digits. This is especially important, given that striated melanonychia may be found in virtually all Africans over 50 years in age as an ethnic feature;
E (extension) - E (extension) - This is the Hutchinson's sign itself,13 which consists of the pigment extending to the periungual region;
F (family) - Family and personal background for dysplastic nevus syndrome and previous melanomas.

Even though each letter has its own importance, the sum of them leads to the possibility of a more accurate diagnosis. Of the six letters of the alphabet utilized for the clinical diagnosis of melanoma, five were present in the case reported.

A presumed diagnosis of subungual melanoma when the Hutchinson's sign is present has proved to be the rule.11,12,13 However, Baran et al.12 focused on three exceptions: benign diseases, nonmelanomous tumors and the illusory condition (pseudo Hutchinson's sign). Accordingly, it might be present in Peutz-Jeghers and Laugier-Hunziquer syndromes, subungual hematoma, ethnic pigmentation, AIDS, drug use (minocycline and zidovudine), as well as Bowen's disease.

A histopathologic examination continues to be the golden standard for confirming melanoma. The lesions in situ may simulate a benign pattern, especially along the contour, with an increase in basal melanocytes and hyperpigmentation with only focal atypia of the melanocytes. Nevertheless, in the middle of the lesion, intense and uniform cytologic atypia is found. Pigmentation is pronounced, resulting in the presence of melanophages in the upper dermis and large melanin aggregates in the corneal layer. Also, lichenoid lymphocytic infiltrate could plausibly blur the dermoepidermal junction. These histopathologic findings were present in the case described. The biopsy can be either incisional or excisional.

Based on the clinical and histopathologic criteria, the prognosis of NAM is worse than cutaneous melanoma, with survival rates over five years varying from 16% to 87%. More than 50% of patients die prior to completing the five years.11 The traditional treatment has been amputation of the affected digit, at the height of the proximal joint, once the margins are freed of the disease. Some studies have assessed the effectiveness of Mohs micrographic surgery for treating the melanoma in situ. Its advantage is to preserve noble tissue for the affected segment to function adequately.13

Detecting the first NAM lesions is fundamental not only for improving the patient's chances of survival, but also for preserving the digit. The physician must be alert and correctly identify any nail alterations that might be suggestive of melanoma, in addition to being aware of the epidemiological data associated with the disease.



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13. Banfield CC, Dawber RP, Walker NP, Stables GI, Zeina B, Schomberg K. Mohs Micrographic surgery for the treatment of in situ nail apparatus melanoma: a case report. J Am Acad Dermatol. 1999; 40:98-9.         [ Links ]



Correspondence to
Ignez Regina dos Santos Muri Mendonça
Rua Dona Mariana, 136/ 204 - Botafogo
22280-020 Rio de Janeiro RJ
Tel./Fax: (21) 2538-0049

Received on December 05, 2001
Approved by the Consultive Council and accepted for publication on September 10, 2003.



* Work done at R D Azulay Dermatology Institute; "Centro de Estudo da Unha- Ceu" (Nail Study Center); "Santa Casa da Misericórdia do Rio de Janeiro", Rio de Janeiro State.

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