Objective  To investigate the clinicopathological features and immunophenotype of inflammatory myofibroblastic tumor (IMT) and their relationship with IMT diagnosis and prognosis.

  Methods  A total of 11 IMT cases with follow-up were analyzed morphologically and immunohistochemically.

  Results  The patients included 6 men and 5 women aged 13-66 years. The tumors were found in various anatomical sites, including lung, mediastinum, liver, intra-abdominal, and bladder. Histologically, the majority of the cases comprised spindled fibroblastic and myofibrobalstic cells accompanied by chronic inflammatory cells in a myxoid or hyalinized stroma; the rest were individual cases of abscess formation. Prognosis mala was indicated for cases with features including atypia tumor cells with two cases demonstrating epithelioid morphology and nucleoli. Immunohistochemical study showed that vimentin, ALK, SMA, S-100, CD117, and CD34 were expressed in 91% (10/11), 55% (6/11), 100% (11/11), 27% (3/11), 18% (2/11), and 9% (1/11) of IMT, respectively. Ki-67 was expressed from 3%-40% respectively. CK, H-caldesmon, and DOG1 were negative in all cases. Follow-up data were available for 11 patients and ranged from 4 to 22 months. Data showed that 7 patients were alive with no evidence of disease; 4 patients were alive with tumor, whereas 3 showed aggressive biological behavior.

  Conclusion  IMTs had intermediate behavior or malignant potential. Most IMTs with aggressive behavior showed a minority of tumor cells with atypia, epithelioid morphology, and nucleoli. High proliferation index expression, ALK, SMA, and H-caldesmon can aid in IMT diagnosis.