Primary inflammatory myofibroblastic tumor of the breast with rapid recurrence and metastasis: A case report.

Primary inflammatory myofibroblastic tumor (IMT) of the breast is extremely rare; only 19 cases have been reported in the English literature. In the present study, we present a case of IMT in a 56-year-old female patient who was admitted to our hospital due to a mass found in her right breast. Mammogram and ultrasound revealed a well-circumscribed mass and surgery was performed. Histopathologically, the lesion was composed of spindle and inflammatory cells, including plasma cells and lymphocytes. Mitotic figures were not observed. Immunohistochemically, the tumor cells were positive for SM-actin, anaplastic lymphoma kinase (ALK) and vimentin and focal positive for desmin, but negative for NSE, S-100, CD117, CD34, NF, CD21, CD35 and CD68. Thus, we made a diagnosis of IMT and advised regular follow-up. However, the patient had local recurrence and metastasis to the left groin area 3, 7 and 10 months after the initial surgery. Notably, the histopathological characteristics of the recurrent and metastatic foci were similar to those of the initial specimen, but mitotic figures were clearly observed. Thus, we conclude that IMT shows occasionally malignant biological behavior although it is a neoplasm of intermediate biological potential that frequently recurs and rarely metastasizes. We advise that clinical physicians should regularly follow up patients after focal resection for IMT.