Mitotic Activity in Juvenile Benign Nevi

Melanocytic nevi are submitted for histological evaluation primarily to exclude a malignant process. Mitotic figures are one of the factors used in this assessment. However, there is a lack of data on mitotic activity in juvenile benign nevi. The authors assessed 114 cases of benign melanocytic nevi in children aged 0-15 (inclusive) years old by counting the mitoses present in 2 sections of hematoxylin and eosin-stained tissue. The authors then calculated the proportion of cases in which mitotic activity was present, and the average number of mitoses per case for each age group to get the mitotic rate. The authors found that there was at least 1 mitoses present in 40.4% of cases, and that the mitotic rate decreases in older children compared with younger children. This highlights the need for careful consideration of the significance of a mitotic figure in juvenile pigmented lesions, to ensure the lesion is not overinterpreted as malignant.