Brief communtcadons

Subungual melanoma in situ presenting aslongitudinal melanonychia in a patient withfamilial dysplastic nevi

Paul Kechijian, MD New York, New York

Although the term dysplastic remains controversial,1

patients with large numbers of dysplastic nevi are at in­creased risk for developing malignant melanoma.2, 3 Thisarticle illustrates the importance of longitudinal mel­anonychia in a patient with many atypical nevi. It alsopresents the first account of subungual melanoma in situin a patient with atypical nevi and a family history ofmelanoma.

Case report. A 36-year-old man had a 4-year history of lon­gitudinal melanonychia of his left thumb. The 3 mm band wasvariegated with slightly blurred lateral margins (Fig. 1). Severalnevi had been removed previously. Histopathologically, theywere interpreted as melanocytic nevi without atypical histologicfeatures. To the patient's knowledge, no other family membershad exceptional nevi or a history of melanoma. Clinical exam­ination revealed multiple nevi that were increased in size andnumber and were morphologically dysplastic. l A biopsy speci·men of the nail matrix revealed atypical melanocytes-singlyand in nests within the epidermis at all levels-and melanoph­ages in the inflammatory cell infiltrate in the upper part of thedermis; the findings were interpreted as malignant melanoma insitu. The diagnosis of melanoma in situ was discussed with thepatient. The implications of atypical nevi were again reviewed.After this conference, the patient spoke with his father andlearned for the first time that a melanoma had previously beenexcised from his father's chest. The father also had atypical nevi.

Discussion. Many features of this case are instructive.First, patients who have multiple atypical nevi should beactively encouraged to inquire whether any first-degreerelatives have unusual nevi or a history ofmelanoma. Thepresence of melanoma in this father and son further sup­ports the concept of familial melanoma.2•3

In addition, the evaluation ofpatients with longitudinalmelanonychia should include a complete cutaneous ex­amination. This case report makes clear the importanceof examining the fingernails and toenails of patients whohave atypical nevi.

The presence of atypical nevi or a history of a previousmelanoma in a patient with longitudinal melanonychiashould prompt the clinician to regard longitudinal mela-

From the Nail Section of the Department of Dermatology, New YorkUniversity Medical Center.

Reprints not available.

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Fig. 1. Pigmented band extends longitudinally fromcuticle to distal margin of nail plate. Light shades ofbrown flank sides of a darker, more central band of pig­mentation with blurred margins.

noma with increased suspicion. In either clinical setting,the diagnosis ofsubungual melanoma should be ruled outby biopsy.4

Color variegation and blurred margins are importantclues to the diagnosis of subungual melanoma.4 Otherclues to the diagnosis of subungual melanoma includeHutchinson's sign (periungual spread of pigmentation tothe surrounding proximal and lateral nail folds), involve­ment of a single digit, inception of banding in an elderlypatient, the abrupt onset of a new band or sudden changein width or color ofa previously "stable" band, associatednail dystrophy, and occurrence oflongitudinal melanony­chia on the thumb or great too.4

Individually and collectively, longitudinal melanony­chia and atypical nevi represent important clinical disor­ders. The possibility of melanoma must always be con­sidered in the presence of either condition. This reportfurther documents the relevance of longitudinal mel­anonychia as a possible sign of subungual melanoma andemphasizes the importance of examining the nails of pa­tients with atypical nevi.

REFERENCES1. Kopf A W, Friedman RJ, Rigel DS. Atypical mole syn­

drome. JAM ACAD DERMATOL 1990;22:117-8.2. Albert LS, Rhodes AR, Sober AJ. Dysplastic melanocytic

nevi and cutaneous melanoma: markers of increased mela­noma risk for affected persons and blood relatives. J AMACAD DERMATOL 1990;22:69-75.

3. BaleSJ, Dracopoli NC, Tucker MA, etal. Mapping the genefor hereditary cutaneous malignant melanoma-dysplasticnevus to chromosome Jp. N Engl J Moo 1989;320:1367-72.

4. Baran R, Kechijian P. Longitudinal melanonychia (mel­anonychia striata): diagnosis and management. J AM ACADDERMATOL 1989;21:1165-75.

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