Lentigo simplex.

There are various kinds of lentigo (pl. lentigines). They tend to have a uniform colour but benign lesions may have some variegation in colour (tan, brown and black). They may evolve slowly or appear suddenly. There are several genetic syndromes associated with extensive lentiginosis.
The lentigo simplex is characterised by a small number of round or oval 3-15 mm brown macules with even or jagged margin, unrelated to sun exposure. Histologically there is increased basal pigmentation due to increased numbers of melanocytes.