Epithelioid inflammatory myofibroblastic sarcomas are not exclusive to ventral cavity sites

Epithelioid inflammatory myofibroblastic sarcoma (EIMS) is a clinically and histologically distinct variant of inflammatory myofibroblastic tumor that is characterized by an aggressive clinical course and dismal prognosis (1). Histologically, EIMS is composed of sheets of rounded or epithelioid cells with vesicular nuclei, large nucleoli, and eosinophilic to amphophilic cytoplasm, that is often set in a myxoid stroma rich in inflammatory cells. A minor spindle cell component is usually present. Most EIMS harbor RANBP2-ALK or RRBP1-ALK gene fusions and only a single putative case harboring an alternate EML4-ALK fusion has been reported (2-3). Notably, the ALK immunostaining pattern varies depending on ALK fusion partner; RANBP2-ALK is associated with nuclear membranous pattern while RRBP1-ALK shows a perinuclear accentuated cytoplasmic pattern. EIMS typically affects male patients and shows a striking predilection for the abdominal cavity. Exceptionally rare cases have been reported in the thoracic cavity (3 in lung/pleura) and pelvic cavity (1 in ovary) (4-7). To our knowledge, EIMS has not been reported outside the ventral cavity.