Intraparenchymal leiomyoma of the breast: report of a case with emphasis on needle core biopsy-based diagnosis.

OBJECTIVE: We report the clinicopathologic features of a rare case of leiomyoma of the breast parenchyma in a 36-year-old female, diagnosed preoperatively at core biopsy. A complete review of the literature on the topic is provided and differential diagnostic problems are discussed. METHODS: Standard histological examination and immunohistochemical analyses using a large panel of antibodies were performed in both the core biopsy and surgical specimen. RESULTS: Ultrasonography revealed a well-circumscribed tumour mass without calcifications. Histological examination of the core biopsy showed proliferation of bland-looking eosinophilic spindle cells arranged in a fascicular growth pattern. Mitoses, pleomorphism and necrosis were absent. Immunohistochemistry, revealing diffuse staining for a-smooth muscle actin, desmin and h-caldesmon, confirmed the leiomiomatous nature of neoplastic cells. Histological and immunohistochemical analyses of the surgical specimen confirmed the definitive diagnosis of leiomyoma. CONCLUSIONS: The present case emphasizes that diagnosis of leiomyoma of the breast parenchyma can be confidentially rendered on needle core biopsy. We believe that correct diagnosis is primarily dependent on the awareness that this tumour can arise in this unusual site on rare occasions.