Ulcerated Storiform Collagenoma

This rare form of benign fibrous tumor can be associated with Cowden's disease. An important differential diagnosis of any fibromatous lesion showing a whorled storiform architecture with neutrophils would be a chronic leukocytoclastic vasculitis, namely erythema elevatum diutinum. One must also be cognizant of a sclerosing perineurioma.