Seasonal variation in the junctional component of pigmented naevi

From an assessment of the presence of a junctional component in 8,380 pigmented naevi, and histological review of its extent and the presence of inflammation and regression in a sample of 216 junctional and compound naevi, it was determined that naevi excised in summer were more likely to have a junctional component and evidence of inflammatory response than those excised in winter. It is suggested that a short-term promotional effect of sunlight on cells in the junctional zone of pigmented naevi may, in addition to increased case ascertainment in summer, explain reported seasonal variation in the incidence of malignant melanoma.