Pleomorphic (sarcomatoid) carcinoma of lung—Cytohistologic and immunohistochemical features

Pleomorphic carcinoma of the lung is a member of sarcomatoid carcinoma family of tumors, which also include spindle and giant cell carcinomas, as well as truly biphasic neoplasms like pulmonary blastoma and carcinosarcoma. These non-small cell tumors are typically associated with aggressive clinical behavior and shortened patient survival. Because of poor tumor differentiation and limitation of sampling at cytology, accurate cytologic tumor subtyping may not be possible. However, recognition of this tumor as primary to lung and its categorization as sarcomatoid carcinoma can facilitate patient– physician interaction, disease management and survival expectation. Our 70-year-old patient was biopsied with a 23-gauge needle under CT-guidance for a 4-cm right upper lobe lung mass that invaded the pleura and was associated with multiple lytic rib lesions. The patient had no clinical and radiologic evidence of an extrapulmonary malignancy. At on-site evaluation, bizarre giant cells were observed (Fig. C-1a) with intracytoplasmic neutrophils. The surrounding poorly differentiated cells were smaller but with similar chromogenic nuclear and cytoplasmic features. The preliminary (onsite evaluation) diagnosis was ‘‘non-small cell malignant neoplasm with giant cells, may represent a primary giant cell tumor of the lung.’’ The remainder of the aspirated material was processed for Papanicolaou-stained slides and a cell block for routine H&E staining and immunohistochemistry. In the alcohol-fixed smears, the cytoplasmic and nuclear features in tumor cells were similar to those seen in air-dried and Diff-Quik stained material (Fig. C-1b). In the cell block, two different cellular/architectural patterns were seen: areas with aggregating giant cells resembling osteoclasts (Fig. C-1c), and spindled and epithelioid tumor cells with entrapped rare giant cells (Fig. C-1d). At immunohistochemistry on cell block, tumor cells were uniformly positive for CK 7 (Fig. C-1e) and Vimentin (Fig. C-1f), focally for CD99 and TTF-1, and negative for Thyroglobulin. Pleomorphic carcinoma of the lung is a challenging diagnosis to make at onsite cytologic evaluation of a lung lesion because of very poor cellular differentiation, though intracytoplasmic neutrophils can be a helpful cytologic feature. The differential diagnoses include poorly differentiated primary squamous and adenocarcinoma, primary sarcoma, metastatic poorly differentiated carcinomas from thyroid or kidney, and metastatic sarcomas like chondrosarcoma, osteosarcoma, or angiosarcoma. Osteoclast-like giant cells have previously been reported in bronchogenic sarcomatoid squamous-cell carcinoma. The definitive diagnosis can only be made with the help of immunohistochemistry, mandating adequate cytologic sampling of the lesion, and appropriate processing of cells. Department of Pathology, University of Tennessee Health Sciences Center, Memphis, Tennessee *Correspondence to: Nadeem Zafar, M.D., M.I.A.C., Department of Pathology, University of Tennessee Health Sciences Center at Memphis, 930 Madison 5th Floor, Memphis, TN 38163. E-mail: nzafar@uthsc.edu Received 7 October 2009; Accepted 1 December 2009 DOI 10.1002/dc.21322 Published online 20 January 2010 in Wiley Online LIbrary (wileyonlinelibrary.com).