All breast tumors originally coded as carcinosarcoma or spindle cell carcinoma in Gunma University Hospital were retrieved and reviewed. A total of 12 cases were identified from 1962 to 1995. Neoplasms were eventually classified as spindle cell carcinoma if in situ or ductal, lobular, squamous, or mixed infiltrating carcinoma was contiguous or subtly merged with sheets of spindle-shaped cells. Tumors in which spindle cell components comprised less than half of the entire tumor were excluded from the category of spindle cell carcinoma. Clinical data of patients were analyzed in conjunction with characteristics such as tumor size, contour, and lymph node metastasis. The content of estrogen receptor or ER and progesterone receptor or PR in the tumors was evaluated by using the dextran coated charcoal method. Spindle cell carcinoma is a rare form of breast tumor. We present herein three cases of spindle cell carcinoma of the breast and review its characteristics from the literature. Spindle cell carcinoma frequently forms a large and well-circumscribed tumor with gross cyst formation.

Histologically, its dominant component is of sheets of spindle shaped cells, and it includes such contiguous carcinoma components as squamous differentiation or invasive ductal carcinoma. Estrogen receptor expression and lymph node metastasis tend to be low. Despite the sarcomatous features, spindle cells are likely to be derived from epithelial cells of mammary glands. Immunohistochemical and ultrastructural examination demonstrated the expression of keratin and the desmosome-like junctional structure in the spindle cell components. Relatively favorable prognosis is expected in spindle cell carcinoma of the breast compared to common breast carcinoma. Spindle cell carcinoma is an unusual neoplasm commonly observed in the oral cavity and the larynx. However, on rare occasions it occurs in the breast. Spindle cell carcinoma consists of dominant spindle shape cells together with in situ or ductal, lobular, squamous, or mixed infiltrating carcinoma. Since the histological arrangement of the spindle cell component resembles sarcoma, the category of `spindle cell carcinoma has been included in carcinoma with pseudosarcomatous metaplasia, carcinosarcoma, or metaplastic carcinoma. Despite its sarcomatous features, immunohistochemical studies have recently suggested that spindle components are likely to be derived from epithelial cells. We present herein three cases of breast spindle cell carcinoma with a cystic formation and review its characteristics from the literature. Immunohistochemical analysis for keratin and vimentin was carried out with the avidin-biotin peroxidase complex or ABC method using formalin-fixed paraffin-embedded tissue sections. Monoclonal anti-keratin antibody KL-1 and monoclonal anti-vimentin antibody M0725 were used for this study. KL-1 was known to react to a variety of cytokeratin molecules, mainly 58 kDa cytokeratin. Conventional electron microscopic observations were made on the last case. Among the 12 cases recorded as carcinosarcoma or spindle cell carcinoma of the breast, three were eligible for this study. Two cases were excluded from this study because of their heterologous metaplastic features with little spindle component. Six cases were classified as invasive ductal carcinoma since their spindle cell components comprised less than half of the entire tumor. One case could not be reviewed due to the lack of the original slide. Three patients with spindle cell carcinoma have been followed up since operation. The clinical characteristics in the three cases of spindle cell carcinoma are summarized in Table. Two patients were premenopausal women and one was postmenopausal. The age ranged from 48 to 63 years with an average of 54 years. Two lesions occurred in the right breast and one in the left breast. The tumors were located in the upper outer quadrant of the breast and showed gradual enlargement prior to the patients visiting our hospital. The tumors were well defined, with cysts which were clearly detected by ultrasonograms. Their sizes ranged from 5.2 to 9.0 cm. No distant metastasis was found in any patients. The preoperative diagnosis was stage IIIa breast cancer according to the Japanese clinical TNM or Tumor Node Metastasis classification system; this is fundamentally the same as the TNM classification. Two patients underwent an extended radical mastectomy with parasternal dissection and one underwent a modified radical mastectomy. The cut surfaces of all specimens were elastically firm and well- circumscribed with gross cysts. Neither ER nor PR was detected in any tumors. All patients received adjuvant chemotherapy and one patient received adjuvant endocrine therapy of tamoxifen. No recurrence has occurred since the operation. Microscopic findings by Hematoxylin and Eosin staining of the three tumors were basically similar. Briefly, the dominant component of the tumor was the bundles of spindle-shaped cells. Some tumor cells possessed atypical nuclei and were arranged in a solid nest. Invasive ductal carcinoma components were found in the tumors of Cases 1 and 2, shown for Case 2 in. Squamous differentiation, i.e. keratinization and intercellular bridging, was observed in the nest of spindle cells in Case 3. However, these carcinomatous components comprised less than half of the entire tumor.