Bizarre Stromal Cells in the Esophagus: A New Case.

Esophageal bizarre stromal cells (BSCs) represent an important diagnostic pitfall, since they can closely resemble a malignancy, thus leading to a significant overtreatment. We recently encountered a case in a healthy 38-year-old man, with a normal blood count, who underwent an upper gastrointestinal endoscopy during the follow-up of a grade I esophagitis and hiatus hernia. The endoscopy revealed an ulcerated sessile polyp that, on histology, consisted of a proliferation of round atypical discohesive cells, with a variable amount of cytoplasm, large nuclei, and prominent eosinophilic nucleoli. They were intermingled with many granulocytes and plump vessels, in a background of granulation tissue. Immunohistochemical stains with pan-cytokeratin, S100, and CD31 were negative and Ki67 stained only very few nuclei. At variance with other anatomical sites and despite the putative fibroblastic or myofibroblastic origin, BSCs in esophagus can have a striking epithelioid appearance, mimicking a carcinoma or a melanoma. Awareness of BSCs can prevent serious misdiagnoses.