Epithelioid inflammatory myofibroblastic sarcoma with recurrence after extensive resection: significant clinicopathologic characteristics of a rare aggressive soft tissue neoplasm

A case of epithelioid inflammatory myofibroblastic scarcoma (EIMS) developing in an 8-year-old boy who presented with a bulky intra-abdominal occupying lesion with recurrence undergoing a radical resection was reported. Histologically, the tumor cells arranged in cords, strands or sheets of round-to-epithelioid cells with a vesicular nuclear chromatin pattern, prominent nucleoli and weakly eosinophic or basophilic cytoplasm embedded in the abundant myxoid stroma with lymphocytes infiltration. They were positive for ALK, Desmin, SMA, CD30, but negative for AE1/AE3, LCA, CD2, CD3, CD5, CD7, S-100, CD34, CD31, EMA, MyoD1, and myogenin. An elevated proliferation index was demonstrated by Ki-67 comparing the first and the second lesion. Fluorescence in situ (FISH) showed the presence of chromosomal translocation involving ALK. This case show EIMS is a rare variant of inflammatory myofibroblatic tumor with aggressive biological behavior and unfavourable prognosis. To be familiar with its significant clinicopathologic characteristics could prompt us to take it into consideration when facing the relevant dieases.