What can you tell me about spiradenoma?

Very rare: Malignant eccrine spiradenoma is a type of tumor that develops from a sweat gland in the skin. It starts as a rapidly-growing bump on the head or abdomen, and may cause tenderness, redness, or an open wound. The exact cause of malignant eccrine spiradenoma is unknown, though it is thought that sun exposure or problems with the immune system (immunosuppression) may contribute.