melanoma in situ

melanoma in situ

A melanoma characterised by pagetoid spread of atypical cells or nests along the epidermal junction, extending up into the epidermis, but not the dermis. The cells are hyperchromatic, angulated and large. Mitoses may be seen.
DiffDx
Shave biopsied intradermal naevus.

mel·a·no·ma in si·tu

(mel'a-nō'mă in sī'tū) A melanoma limited to the epidermis and composed of nests of atypical melanocytes and scattered single cells extending into the upper epidermis; local excision is curative although the lesion, if untreated, may soon invade the dermis. Malignant lentigo may be considered a slowly progressive type of melanoma in situ.