The presence of bizarre stromal cells has been reported in various gastrointestinal and extraintestinal lesions, mostly within the granulation tissue in the ulcer bed. The morphologic spectrum of bizarre stromal cells suggests a differential diagnosis, which includes carcinoma, lymphoma or sarcoma.
Immunohistochemistry (positivity for vimentin only, or less commonly for smooth muscle actin), together with an awareness of those atypical stromal cells occasionaly occuring in the setting of ulceration and/or polypoid lesions, prevents an incorrect diagnosis.