FUS::CREM‐rearranged malignant epithelioid neoplasm mimicking neuroendocrine neoplasm of unknown primary

A 76-year-old women presented with abdominal pain. Diagnostic investigations suggested peritoneal carcinomatosis. Histological examination of laparoscopic biopsies showed large epithelioid cells forming sheets intermingled with some lymphocytes. There was no clearly distinguishable stroma. Immunohistochemistry showed diffuse and strong expression of cytokeratin AE1/AE3, synaptophysin and chromogranin-A.