Three patients with spindle cell carcinoma located in the lower respiratory tract are presented, including cases of two monophasic and one biphasic tumor. On light microscopic examination, the spindle cell components of the tumors were histologically characterized by sheets of fusiform spindle cells that closely resembled a sarcoma. Keratin expression in the spindle cell components of these tumors, as shown by anti-cytokeratin antibody staining, demonstrated their epithelial nature. It is supposed that the spindle cell component displays a spectrum of phenotypes originating from epithelial cells with varying degrees of mesenchymal transformation. It is difficult to establish a diagnosis of this rare primary pulmonary malignancy prior to surgical intervention. A review of the literature allowed for a summary of the clinicopathologic characteristics of this tumor.

Biphasic and monophasic sarcomatoid carcinomas of the lung. A reappraisal of 'carcinosarcomas' and 'spindle-cell carcinomas'.Am J Clin Pathol. 1994 Sep;102(3):331-40.

To address the premise that pulmonary "carcinosarcomas" and spindle-cell carcinomas are part of a single clinicopathologic continuum, the authors studied 21 examples of such lesions as defined by World Health Organization criteria. Two biphasic tumors demonstrated an admixture of overt carcinoma with other foci showing partial rhabdomyogenic differentiation; 15 others were histologically similar but lacked "heterologous" sarcoma-like elements; and four lesions were monophasic spindle-cell sarcomatoid carcinomas. One of the latter also contained rhabdomyosarcoma-like areas by light microscopy. Sarcomatoid components were reactive for keratin and/or epithelial membrane antigen (EMA) in 18/21 cases. In addition, desmin and muscle-specific actin were co-detected in the same spindle cells that were keratin-positive in 4 tumors, 3 of which were those with partially myogenic histologic features. Vimentin was present in keratin- or EMA-reactive sarcomatoid cells in 12 neoplasms, and all cases were labeled with an antibody to collagen type IV. Survival was poor in this group of patients; only 1 was alive at last contact. These data support the contention that "carcinosarcoma" of the lung is part of a spectrum with "spindle-cell carcinoma." It is proposed that the terms "biphasic sarcomatoid carcinoma" and "monophasic sarcomatoid carcinoma" are more apt descriptors for such tumors.

Lung carcinoma with spindle cell components: sixteen cases examined by immunohistochemistry.Hum Pathol. 1992 Nov;23(11):1289-97.

Sixteen cases of lung carcinoma with spindle cell components were studied by conventional histochemistry and immunohistochemistry. The epithelial components were squamous cell carcinoma in six cases, adenocarcinoma in four, adenosquamous carcinoma in five, and large cell carcinoma in one. In every case sarcomatous areas were distinctly observed and, in general, neoplastic spindle cells proliferated in close proximity to the epithelial elements. Some of the histochemical procedures suggested mesenchymal features in the stroma of the exophytic portions of three cases, but heterogeneous elements, such as bone or striated muscle, were not observed. By immunohistochemical examination the epithelial elements showed positive reactions for keratin, epithelial membrane antigen, and/or carcinoembryonic antigen to a varying degree according to the histologic types. The spindle cell elements revealed a positive immunoreaction for keratin in all but one case. Epithelial membrane antigen was demonstrated in sarcomatous areas of only five cases and carcinoembryonic antigen was not expressed at all. In contrast, vimentin was distinctly demonstrated in sarcomatous areas of five cases, although other mesenchymal markers, such as desmin, actin, and myosin, were negative. These findings indicate that the spindle cell components in these 16 cases may represent mesenchymal features with partial or complete loss of epithelial features.

A case of spindle cell (squamous) carcinoma (WHO) of the lung.  Nihon Kyobu Shikkan Gakkai Zasshi. 1991 Dec;29(12):1608-13.

A 76-year-old man with spindle cell (squamous) carcinoma of the lung developed fatal respiratory failure after limited thoracic irradiation at a total dose of 18 Gy. He developed severe pulmonary toxicity, which presented as dry cough, dyspnea, and pulmonary infiltrates extending beyond the radiation field. Microscopically, a transitional form of squamous to spindle-shaped cells was observed in the primary tumor, located at right S8. Immunohistochemical examination showed positive staining of spindle cells for keratin, vimentin, and EMA, but not for desmin. These results indicate that the spindle cells had characteristics of squamous epithelial cells, and differed from carcinosarcoma. Distant metastatic lesions were composed of only the spindle cell component.

Spindle cell carcinoma of the lung. A clinicopathologic study of three cases.Cancer. 1991 May 1;67(9):2361-7.

Two cases of monophasic spindle cell carcinomas and one case of adenosquamous carcinoma with the spindle cell component located in the lower respiratory tract are presented. In the biphasic tumor, areas of transition from carcinoma to sarcomatous spindle cells were clearly found. The two monophasic tumors and the spindle cell component of the biphasic tumor were histologically characterized by sheets of spindle cells. However, by electron microscopic and immunohistochemical study, several features of squamous epithelial differentiation were found in the spindle cell areas of all cases. Keratin and vimentin were, in various degrees, coexpressed in all the cases. Therefore, it is supposed that the spindle cell component displays a spectrum of phenotypes originating from squamous cell carcinoma, and monophasic spindle cell carcinoma is considered as a kind of the extreme phenotype of squamous cell carcinoma pretending mesenchymal differentiation.

Spindle cell squamous carcinoma of the lung. Immunocytochemical and ultrastructural study of a case. Histopathology. 1987 Aug;11(8):871-8.

A case of squamous cell carcinoma of the lung showing extensive spindle transformation is presented. On light microscopy, the tumour showed sheets and fascicles of elongated fusiform cells resulting in a growth pattern which closely resembled a sarcoma. Immunocytochemistry using tissue-specific antibodies against intermediate filaments demonstrated exclusive labelling of the tumour cells with prekeratin antibodies. Electron microscopy showed well-formed intercellular junctions and thick bundles of tonofilaments within the cytoplasm of the cells further confirming the squamous epithelial nature of the neoplasm. The findings in the present case point to the existence of a non-metaplastic spindle cell variant of squamous carcinoma of the lung. The possible mechanisms which may account for the spindle shape of the cells are reviewed.

Spindle cell squamous carcinoma of the lung--two case reports.Gan No Rinsho. 1987 Mar;33(3):293-9.

Two cases of spindle cell squamous carcinoma of the lung are presented. Both cases were female heavy smokers aged 73 and 55. The carcinomas, 7.5 and 6.0 cm in diameter respectively, were located at the peripheral portion of the right lower lung lobes. Direct invasion to the diaphragma and metastasis to the chest wall were observed in the first case but no metastasis was observed in the second case. Histologically, both carcinomas showed a biphasic appearance due to the presence of a squamous cell carcinoma component and a spindle cell sarcomatous component with marked cellular pleomorphism, but no neoplastic bone, cartilage or muscle. Transitional area of two components were seen in the second case.