GP Quiz 11 - Case 2.
A 23-year-old footballer asks you to look at his great toenail, which has been worrying him for some months. He thinks his boots may have been too tight, and wonders if he's picked up a fungal infection from the changing rooms. You notice that part of the toenail is missing, the residual nail plate is discoloured and the nail bed is ulcerated.
What is the likely diagnosis?
Ulcerated malignant melanoma of the nail apparatus. More than 50% patients with nail apparatus melanoma present late because the diagnosis has not been considered. Characteristically, the lesion starts as an irregular and expanding pigmented band in the nail plate (melanonychia striata) extending onto the adjacent nail fold (Hutchinson's sign). Nail apparatus melanoma accounts for 1-2% of all cases of melanoma. It is not associated with specific ethnicity or with sun exposure. Squamous cell carcinoma may also affect the nail, but is less likely in a young adult.
What should you do to prove it?
You should urgently refer the patient to a plastic surgeon or dermatologist for an opinion and biopsy. If confirmed, the melanoma should be excised. Excision will entail amputation of the digit. No other treatment has been demonstrated to affect survival rates - the prognosis of a nail apparatus melanoma is disproportionately poor compared with melanoma arising elsewhere with overall 5-year survival rates of about 50%.
This quiz was also published by ADIS International in in February 2003.