CLINICOPATHOLOGICAL FEATURES OF SMALL-DIAMETER MALIGNANT-MELANOMA

To assess the frequency, the clinical aspects and the histological typ e of small diameter (<1 cm) malignant melanoma (small CMM), we retrosp ectively reviewed a series of 762 primary cutaneous melanomas. One hun dred and twenty-one small CMM (15.8%) were found, 27 in situ CMM inclu ded. The SSM type accounted for 71.1% of cases and the NM type for 20. 7%, while 5 cases were LMM, 2 ALM and 3 unclassifiable melanomas. Amon g invasive CMM, the mean thickness was 1.28 mm (+/-0.85) (range 0.28 - 3.80). Lesions with favourable prognosis (in situ CMM plus invasive C MM less than 0.76 mm in thickness) represented 47.9% of cases. The cri teria of the ABC rule (asymmetry, irregular border, variegated colour) were simultaneously present in 26.6% of lesions. Conversely, 14.4% of cases showed none of these criteria. In conclusion, a large number of ''small'' CMM exceeded the thickness related to a good prognosis; mor eover, the small CMM were not easily identifiable: only 26% of lesions satisified the ''ABC'' rule. In our opinion, the early diagnosis of C MM should be improved also emphasizing the evolution of the lesion (AB CD + E).