Spitz nevus versus malignant melanoma: spitz nevi predominate on the thighs in patients younger than 40 years of age, melanomas on the trunk in patients 40 years of age or older.

Abstract

To determine whether location and gender in addition to patient age might be useful in discriminating parameters between malignant melanoma (MM) and Spitz nevus (SN); 1228 cases of MM and 967 cases of SN were analyzed. Computerized records were studied and compared as to frequency and density, and the results were statistically analyzed. Spitz nevi (SNs) were found to predominate on the thighs (32.6 % of the cases in women, 19.9 % of the cases in men); in persons younger than 40 years of age, in both genders they were found 8.1 times more frequently than MM in this location. In contrast, MMs on the trunk in persons 40 years of age or older in both genders were 7.4 times more frequent compared with SN. There has been no follow-up of the patients, and the question whether SN are benign tumors was not assessed. The only locations that appear to be of additional diagnostic help when differentiating between these two tumors are the thighs in patients younger than 40 years of age, suggesting SN, and the trunk in patients 40 years of age or older, suggesting MM.