The ABC rule for clinical detection of subungual melanoma

Background: Subungual melanoma is a relatively rare disease with reported i ncidence between 0.7% to 3.5% of all melanoma cases in the general populati on. Unlike the significant improvement in the diagnosis of cutaneous melano ma, the diagnosis of subungual melanoma has shown little, if any, improveme nt over the years. The widespread adoption of the ABCDs of cutaneous melano ma has helped increase public and physician awareness, and thus helped incr ease the early detection of cutaneous melanoma; the same criteria cannot be applied to the examination of the nail pigmentation. Objective: We reviewed the world literature an subungual melanoma and arran ged the available information into a system for the identification of subun gual melanoma. This system has to be thorough, easy to remember, and easy t o apply by both physician and lay public. A case to illustrate the delayed diagnosis often encountered in the current evaluation of nail melanoma is p resented. Methods: A thorough review of the world literature on subungual melanoma wa s undertaken. The important findings of various studies and case reports we re compared among themselves and the salient features were summarized. The information was then categorized under the easily recalled letters of the a lphabet, ABCD, that have already become associated with melanoma. Results: The most salient features of subungual melanoma can be summarized according to the newly devised criteria that may be categorized under the f irst letters of the alphabet, namely ABCDEF of subungual melanoma. In this system A stands for age (peak incidence being in the 5th to 7th decades of life and African Americans, Asians, and native Americans in whom subungual melanoma accounts for up to one third of all melanoma cases. B stands for b rown to black band with breadth of 3 mm or more and variegated borders. C s tands for change in the nail band or lack of change in the nail morphology despite, presumably, adequate treatment. D stands for the digit most common ly involved; E stands for extension of the pigment onto the proximal and/or lateral nailfold tie, Hutchinson's sign); and F stands for family or perso nal history of dysplastic nevus or melanoma. Conclusion: Although each letter of the alphabet of subungual melanoma is i mportant, one must use all the letters together to improve early detection and thus survival of subungual melanoma. Still, as with cutaneous melanoma, the absolute diagnosis of subungual melanoma is made by means of a biopsy.