Our results, indicating that smooth muscle differentiation occurs in a minority of the myofibroblastoma cells exclusively in half of the analysed cases, support the separation of myofibroblastoma from leiomyoma. The detection of smooth muscle cells in breast myofibroblastoma is easily explained if we postulate its histogenesis from the CD34+ fibroblasts of mammary stroma capable of multidirectional mesenchymal differentiation, including smooth muscle. We recommend retention of the term myofibroblastoma for all the desmin-positive and/or alpha-smooth muscle actin-positive spindle cell tumours of the breast consistent with the previously well-established morphological criteria for such neoplasms, unless one is dealing with a typical leiomyoma easily recognizable at light microscopy.

We describe the clinical, radiological and pathological features of a series of six cases of primary fibromatosis of the breast. Most patients (5 of 6) were women of 22-58 years of age; one case occurred in a 47-year-old man. The fibromatosis of the breast in all cases presented as a monolateral solid nodule, clinically suspicious for malignancy and in three cases was also associated with cutaneous and/or nipple retraction. None of the patients was affected by any genetic disorder characterized by fibromatoses involving multiple sites, including breast. Both echographic and mammographic examinations revealed solid masses with irregular margins but without calcifications, mimicking scirrhous carcinoma. All cases were surgically treated by lumpectomy (4 of 6) or quadrantectomy (2 of 6), and after a follow-up period ranging from 5 months to 13 years all patients are well and disease-free. Histological examination revealed finger-like infiltrating margins entrapping adjacent breast parenchyma and adipose tissue in all cases. The hallmark of the lesion was the presence of bland-looking spindle cells, with a low mitotic index, organized in long sweeping and intersecting fascicles. Three different morphological phases (i.e. proliferative, involutional and residual), identical to those observed in Dupuytren's superficial fibromatosis, variably coexisted in each case. At immunohistochemistry the cells which comprised the lesion exhibited a diffuse expression of vimentin and a heterogeneous immunoreactivity to a-smooth muscle actin, thus confirming their fibro-myofibroblastic nature. No expression of estrogen, progesterone or androgen receptors or of pS2 correlated-estrogen protein was observed. We discuss both the pathogenesis of the mammary fibromatosis, pointing to the fibroblastic cells of the mammary stroma as the putative precursors, and the differential diagnosis versus the bland-looking, monomorphic spindle cell tumor-like or tumorous lesions of the breast.

No abstract

We herein report the clinicopathologic features of a rare case of biliary adenofibroma (BAF) of the liver in a 79-year-old man. Grossly, tumour presented as a well-circumscribed, 5.5-cm mass with a solid and microcystic appearance. Histological examination was typical of biliary adenofibroma, showing a proliferation of variable-sized tubulocystic structures embedded in a moderately cellular fibrous stroma. Immunohistochemistry, revealing immunoreactivity of the epithelial component to cytokeratins 7 and 19, was consistent with a bile duct origin. Notably, the stromal cells had a myofibroblastic profile, showing a diffuse and strong expression of vimentin and α-smooth muscle actin. Differential diagnosis with Von Meyenburg complex, biliary adenoma, biliary cistadenoma, congenital biliary cystsy, and hepatic benign cystic mesothelioma is provided. The occasionally reported expression of p53 in biliary adenofibroma has suggested that this tumour could represent a premalignant lesion. The absence of both cytological atypia and p53 immunoreactivity in our case confirms that BAF is a benign tumour with an indolent clinical behaviour. However, a careful histological examination of BAF is mandatory because malignant transformation of the epithelial component has been documented in two cases.