Epithelioid Hemangioendothelioma of the Bowel in Crohn's Disease: The First Reported Case.

BACKGROUND: Epithelioid hemangioendothelioma (EHE) is an uncommon malignant endothelial neoplasm that most commonly arises in soft tissue, bone, lung, and liver. Crohn's disease (CD) is an inflammatory bowel disease of unknown etiology that is frequently associated with complications including strictures, fistulas/fissures, and neoplasms.

CASE DESCRIPTION: A 43-year-old woman with a 6-year history of severe CD presented with anal pain and bleeding. She had prior partial colectomy for a stricture and a diverting ileostomy for perianal fissures and stricture. Colonoscopy showed severe chronic active colitis, stricture at 30 cm of anal verge, and a perianal fistula. The patient underwent total proctocolectomy. The colonic mucosa exhibited segmental ulceration and irregular thickening of the colon wall. Beneath an ulcer of the anal canal within the muscularis propria was a 1.2-cm poorly circumscribed, firm, white-tan mass. The mass was composed of cords and groups of large epithelioid endothelial cells with intracytoplasmic vacuoles enmeshed in a myxohyaline stroma. Immunohistochemically, the tumor cells were positive for ERG, CD31, and CAMTA1 and focally positive for keratin and SMA. Next-generation sequencing revealed a WWTR1-CMATA1 fusion. The morphology, immunoprofile, and molecular genetics were diagnostic of EHE.

DISCUSSION: Long-standing inflammatory bowel disease is associated with significant risk for developing neoplasms, usually carcinomas, which can be indistinguishable radiologically and clinically from nonneoplastic complications. These tumors are often identified as an incidental finding in specimens resected for clinically severe disease. This is the first report of EHE arising in the bowel affected by CD, and it mimicked mural fibrosis and fissures.