Inflammatory Myofibroblastic Tumor (InflammatoryFibrosarcoma) of the Lung: A Case Report

ABSTRACT

Inflammatory myofibroblastic tumor, also known as inflammatory fibrosarcoma, has been frequently diagnosed as inflammatory pseudotumor. Although there are six cases reported as inflammatory pseudotumors or inflammatory myofibroblastic tumors in the lung, no cases of pulmonary inflammatory myofibroblastic tumor with features of inflammatory fibrosarcoma have been reported in Korea. We experienced a case of inflammatory myofibroblastic tumor (inflammatory fibrosarcoma)characterized by high cellularity, severe nuclear pleomorphism, necrosis, or increased mitoticcounts. A 31-year-old male patient with a solitary pulmonary nodule on the routine chest x-rayreceived a right lower lobectomy. The tumor was an ovoid solid mass with multifocal necrosis, showing diffuse irregular proliferation of spindle cells with high cellularity and focal nuclear pleomorphism, admixed with dense lymphoplasmacytic cells. Although spindle cells are focally immunoreactivefor smooth muscle actin, the ultrastructural examination failed to demonstrate smooth muscledifferentiation. In cases of inflammatory myofibroblastic tumor (inflammatory fibrosarcoma), a completeexcision and close follow-up without radical surgery, radiation, or chemotherapy are needed.