Primary cutaneous melanoma in hidden sites is associated with thicker tumours - a study of 829 patients.

The aim of this study was to determine if primary cutaneous melanomas in hidden anatomical sites were associated with thicker tumours. Retrospective medical data of 829 patients with melanomas diagnosed at our centre between January 1976 and July 1998 were recorded from our database. Three groups were defined according to the anatomical site of the primary melanoma: (1) visible areas (group 1: 493 patients); (2) visible areas only to the patients or to their partners in privacy (group 2: 281 patients); and (3) hidden areas (group 3: 55 patients). Univariate analysis indicated that patients with melanoma in hidden regions presented significantly thicker tumours (median for group 3: 2.25 versus 1.17 for group 1 and 1.42 for group 2). This group were also more commonly males (group 3: 58% men versus group 1: 38% and group 2: 51%), in a more advanced stage (metastatic disease at diagnosis in 16% of patients in group 3 versus 6% in groups 1 and 2) and at a more advanced age (median group 3: 66 years versus group 1: 59 years and group 2: 51 years), than patients in the other two groups. The association between tumour thickness and body site remained statistically significant after a multivariate analysis. As a delay in diagnosis may be responsible for the thicker size of melanoma in the hidden areas, preventive programmes should stress the importance of not forgetting these locations in self-examination and screening. Special attention should be given to educating elderly men.