Spectrophotometric analysis of melanocytic naevi during pregnancy.

Malignant melanoma is the most common cancer during pregnancy, but it is unknown whether melanocytic naevi in general are activated. A total of 381 melanocytic naevi in 34 Caucasian primigravidae were examined using spectrophotometric intracutaneous analysis (SIAscopy) technology in early pregnancy and prior to delivery. The Siagraphs of each naevus were then compared in order to evaluate changes over time. A total of 163 melanocytic naevi in 21 nulliparous women served as an additional control group. At the first visit none of the Siagraphs examined for the case or control groups aroused suspicion of dysplastic naevus or melanoma and no significant structural changes were noted during the observation period. However, 2.1% of the melanocytic naevi in the pregnant group increased and 1.3% decreased in size. Corresponding figures in the non-pregnant group were 1.8% and 0%, respectively. Only one naevus in a pregnant woman increased slightly in epidermal pigmentation, and a decrease in pigmentation was noted in 3.7% of the melanocytic naevi in the cases and 1.8% in the controls. None of the differences within or between the groups was statistically significant. We conclude that pregnancy does not influence the appearance of pigmented naevi. A changing naevus during pregnancy should be examined carefully and considered for excision and histopathology.