Inflammatory Myofibroblastic Tumor of the Breast Mimicking Malignancy in an Elderly Male.

BACKGROUND: Inflammatory myofibroblastic tumor (IMT) is a rare, distinctive lesion composed of a proliferation of myofibroblastic spindle cells accompanied by an inflammatory infiltrate. It was first described in the lung, but its occurrence at various extrapulmonary sites has also been reported. The literature mentions only a handful of cases of IMT in the breast and only 1 case in the male breast. We report the second case of IMT in the male breast. CASE REPORT: A 60-year-old male presented with a large, lobulated lump in the left breast that had progressively increased in size during the past year. The lump measured 15 × 10 cm. Ultrasonography revealed a solid mass lesion with regular borders in the subcutaneous plane of the left anterior chest wall. Fine-needle aspiration cytology showed a cellular mesenchymal tumor. Macroscopically, the nodule was firm, circumscribed, and yellow. On microscopic examination, the tumor was composed of bland spindle cells arranged in sheets and short fascicles along with a rich inflammatory infiltrate comprising predominantly plasma cells, admixed with lymphocytes, neutrophils, and eosinophils. On immunohistochemistry, the tumor cells were positive for vimentin, focally positive for smooth muscle antigen, and negative for anaplastic lymphoma kinase, CD34, S100, ß-catenin, and cytokeratin. Thus, a final diagnosis of IMT was rendered. CONCLUSION: IMT is a rare entity with intermediate clinical behavior. Knowledge of this entity and its recurrence and metastatic potential is of paramount significance to guide appropriate treatment and follow-up.