Primary cutaneous melanoma: correlation between clinical and histologic aspects in a retrospective Italian study

In Italy, the incidence of new cases of melanoma is roughly 10,000 cases per year, with an average rate of mortality of 5-6 per 100,000 population per year respectively. The objective of this retrospective study was to evaluate the epidemiological incidence of primitive melanoma, including the incidence of multiple melanomas occurring in the same patient. Furthermore, we studied all histological different types of melanoma focusing on the presence of an association nevus-melanoma.

A clinical epidemiologic retrospective study from January 2010 to March 2015 was recorded. For each lesion, mitotic rate, Breslow's index, ulceration, presence of regression, vascular and perineural invasion, lymphocytic infiltrate, microsatellitosis and presence of pre-existencing nevus were also studied.

Five hundred eighty primitive cutaneous melanomas (CMs) were removed from 525 patients with an incidence of 18-20 new melanomas/100,000 habitants/year. Eighty percent of these were at stage T0-1. Among other melanomas, SSM was the predominant subtype (85% of cases). Only 18 cases had lymph node metastases and 13 (2%) lymph node and/or distant metastases (stage IV) at time of diagnosis. Mitotic figures were present in 25% of cases (143 cases out of 580) without significant gender differences.

The incidence of new melanomas founded is close to the CM's incidence in US population in 2016 with a high percentage of superficial melanomas highlighting the importance of prevention campaigns. The presence of melanoma on a preexisting nevus in only 16% of cases allow to conclude that this association is overestimated in literature. On the contrary the high incidence of a second melanoma in the 7% of cases in a relatively short period of survey leads to the conclusion that this data is underestimated.