Periocular cutaneous melanoma arising in a radiotherapy field.

A 78-year-old woman had a periocular cutaneous melanoma in the radiation field of a meningioma. A medial canthal melanoma arose 32 years after primary radiation for a sphenoid wing meningioma and 22 years after supplemental radiation for meningioma recurrence. Histologic sections taken from skin surrounding the melanoma showed widespread melanocytic atypia and 2 separate foci of melanoma in situ. Cutaneous melanoma can arise in a radiation field after a long latency period and should be considered an uncommon form of secondary malignancy.