Practical approach to diagnosis of bland-looking spindle cell lesions of the breast.

The diagnosis of bland-looking spindle cell lesions of the breast is often challenging because there is a close morphological and immunohistochemical overlap among the different entities. The present review will discuss reactive spindle cell nodule/exuberant scar, nodular fasciitis, inflammatory pseudotumor, myofibroblastoma (classic type), lipomatous myofibroblastoma, palisaded myofibroblastoma, benign fibroblastic spindle cell tumor, spindle cell lipoma, fibroma, leiomyoma, solitary fibrous tumor, myxoma, schwannoma/neurofibroma, desmoid-type fibromatosis, dermatofibrosarcoma protuberans, low-grade fibromatosis-like spindle cell carcinoma, inflammatory myofibroblastic tumor and low-grade myofibroblastic sarcoma arising in the breast parenchyma. The pathologist should be aware of each single lesion to achieve a correct diagnosis to ensure patient a correct prognostic information and therapy. Accordingly representative illustrations and morphological/immunohistochemical diagnostic clues will be provided.

Lipomatous myofibroblastoma of the breast: case report with diagnostic and histogenetic considerations.

We report rare case of myofibroblastoma (MFB) of the breast comprised predominantly of a mature fatty component, representing approximately 70% of the entire tumour area. This tumour, designated "lipomatous MFB", should be interpreted as the morphological result of an unbalanced bidirectional differentiation of the precursor mammary stromal cell, with the adipocytic component overwhelming the fibroblastic/myofibroblastic one. Lipomatous MFB is a rare variant of mammary MFB, which can mimic malignancy because of the close juxtaposition of fibroblasts/myofibroblasts with mature adipocytes, resulting in a finger-like infiltrative growth pattern of the former towards the latter. Histogenetic considerations and differential diagnostic problems with other bland-looking spindle cell tumours containing infiltrating fat are provided.

Lipomatous angiomyofibroblastoma of the vulva: diagnostic and histogenetic considerations.

We report a rare case of angiomyofibroblastoma (AMFB) of the vulva, composed predominantly of a mature fatty component, representing approximately 60% of the entire tumour. The tumour, designated as "lipomatous AMFB", should be interpreted as the morphological result of an unbalanced bidirectional differentiation of the presumptive precursor stromal cell resident in the hormonally-responsive stroma of the lower genital tract, with the adipocytic component overwhelming the fibroblastic/myofibroblastic one. The close admixture of adipocytes with spindled/epithelioid cells of the conventional AMFB resulted, focally, in a pseudo-infiltrative growth pattern and pseudo-lipoblast-like appearance, raising problems in differential diagnosis, especially with well-differentiated lipoma-like liposarcoma and spindle cell liposarcoma. Awareness of the possibility that vulvo-vaginal AMFB may contain large amount of lipomatous component is crucial to avoid confusion with other bland-looking spindle cell tumours containing infiltrating fat.

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.

Lipoblast-like signet-ring cells in neurofibroma: a potential diagnostic pitfall of malignancy.

Benign peripheral nerve sheath tumours, including neurofibroma, may occasionally contain a heterologous mature fatty component. Additional lipoblast-like cells can be occasionally identified among mature adipocytes. We report the first case of a plexiform neurofibroma from a NF1 patient containing exclusively lipoblast-like cells exhibiting morphological and immunohistochemical features identical to univaculoted lipoblasts typically seen in myxoid liposarcoma. Awareness of the possibility that an otherwise typical neurofibroma may contain lipoblast-like cells is crucial for the pathologist to avoid a misdiagnosis of malignancy. Differential diagnostic problems and histogenetic considerations are provided.