ABSTRACT
Purpose To explore the clinicopathologic characteristics, immunophenotype, diagnosis and differential diagnosis, molecu-lar genetic feature, treatments and prognosis of intra-abdominal EIMS. Methods Two cases of intra-abdominal EIMS were studied with clinical manifestations, histology and immunohistochemical staining, and its clinical and pathological findings were further ana-lyzed with review of the literature. Results Case 1 was a 15-year-olds male and case 2 was a 21-year-olds female both of whom pres-ented with abdominal pain. Two patients were treated by surgical excision. Microscopically the tumor consisted of two different histolog-ical types, one of which was of high cell density and the other with low cell density and myxoid stroma. Both of these areas contained inflammatory cells, mainly neutrophils with few lymphocytes and plasmocytes. Tumor cells had an epithelioid phenotype with round nu-clei and small nucleoli, various nuclear atypia and mitotic figures were also found, which consistented with the diagnosis of epithelioid inflammatory myofibroblastic sarcoma. Immunohistochemical analysis revealed that the tumor cells were positive for ALK, vimentin, desmin, and CK(AE1/AE3) (focal), and were negative for Calretinin, CD30, CD31, CD33, SMA, HHF35, Myogenin, S-100, HMB-45, CD20, CD79a, CD3, CD5, CD45 and CD68. ALK rearrangement was identified in both cases by FISH using ALK break-a-part probe. Conclusions As an extremely rare tumor, the distinguishing between epithelioid inflammatory myofibroblastic sarcoma and conventional inflammatory myofibroblastic tumor is important. ALK inhibitors are theoretically useful for treating these tumors.