Primary cutaneous extraskeletal osteosarcoma under a previous electrodessicated actinic keratosis.

Extraskeletal osteosarcoma represents approximately 1% of soft tissue sarcomas and approximately 4% of all osteosarcomas. It is therefore much rarer than osteosarcoma arising primarily in bone. Skin as a primary site has seldom been reported. This report describes an extraskeletal osteosarcoma of the skin under a previously electrodessicated actinic keratosis.