This 40-year-old African-American woman has a long history of Crohn disease and partial colectomy. She later developed large ulcerating plaques under her breasts, inguinal region, and perineum. She has been refractory to many therapies. Histopathology confirmed the diagnosis of cutaneous Crohn disease ("metastatic Crohn disease" given the breast involvement). The histology is typical for Crohn disease, with noncaseating granulomas. The histologic differential diagnosis would include sarcoidosis and infectious processes, but the clinical history leads us to the correct diagnosis.
At higher power of the same lesion, the infiltrate is made up of a mixture of histiocytes, lymphocytes, and scattered granulocytes. Histiocytes form loose noncaseating granulomas with multinucleated giant cells. Polarizable material was not found (not shown).