Thursday 3 January 2013
Definition: The lentiginous nevus is a entity which appears to represent the evolution of a lentigo simplex into a junctional and sometimes a compound nevus. It has also been called nevoid lentigo and nevus incipiens.
They are well-circumscribed, sometimes deeply pigmented, often quite small lesions, found most frequently on the trunk of adults between the ages of 20 and 40 years.
At the advancing edge there is a lentiginous proliferation of melanocytes resembling that seen in a simple lentigo, whereas in the more central areas there is junctional nest formation and sometimes a small number of mature intradermal nevus cell nests as well.
Elongation of the rete pegs and some melanophages in the papillary dermis are usually present.
The hypermelanotic nevus appears to be a closely related entity characterized by dark brown to black macules or papules, often on the back, and prominent melanin pigmentation histologically.
The pigment is present in the stratum corneum, in keratinocytes and nevomelanocytes in the basal layer, and in melanophages in the upper dermis.