Lentigo (pl. lentigenes) describes a few common, benign conditions of the epidermis. Lentigenes are acquired lesions that are usually related to sun exposure in youth. They ares significant because although benign, they may progress towards malignant change. With increasing epidermal dysplasia, the pre-malignant lentigo maligna is formed; when this invades beyond the basement membrane it becomes a lentigo maligna melanoma.
Histologically, there is linear hyperpigmentation of the epidermal basal cell layer and an increased number of melanocytes.
Typically, the resulting lesions are 5-10 mm oval macules, with a tan-brown colour. They are found equally amongst the different races and sexes, and they occur in all age groups. Unlike freckles, lentigenes do not darken in response to sunlight exposure and tend to persist in the absence of sunlight. The exception to this is solar lentigo, which occurs after sun exposure.
Recognised types of lentigo include:
Last reviewed 01/2018