Multiple primary cutaneous melanomas.

Abstract

Development of multiple primary cutaneous melanomas is a well-recognized phenomenon. As with single primary melanoma, personal and family histories of melanoma and dysplastic nevi (DN) are considered important risk factors. The natural history and impact of regular follow-up evaluation of this entity were examined. Through a search of the computerized data bank of the Pathology Department and the Melanoma Registry of the Pigmented Lesion Clinic at Massachusetts General Hospital, 41 patients with multiple cutaneous melanomas were identified. Mean (+/- standard error) age at first diagnosis was 49 +/- 2 years (range, 21-75 years). The male to female ratio was 2:1. The median number of primary melanomas was two (88%). Three patients had three and one had five. Melanoma types included superficial spreading (70%), nodular (8%), lentigo maligna (2%), and unclassified (10%), and in 7% the type was unknown. Nineteen (46%) patients had histologic and/or clinical evidence of DN. For the group with DN, the mean age at first diagnosis (44 +/- 3 years) was significantly less than that of patients without DN (54 +/- 3 years) (P less than 0.05). Family history of melanoma was found in 10 patients (24%). Multiple melanomas were diagnosed concurrently in 16 patients (39%), whereas in 25 (61%) diagnosis was sequential. For the latter group, the mean tumor thickness from the first (1.21 +/- 0.28 mm) to the second melanoma (0.51 +/- 0.08 mm) decreased significantly (P less than 0.05); the median time interval was 36 months (range, 2-372 months). These data confirm the need for complete skin examination for patients with newly diagnosed melanoma; and, with subsequent melanomas appearing as long as 31 years after the first melanoma, continued follow-up with complete skin examinations seems prudent.