Transthoracic fine-needle aspiration biopsy of pulmonary spindle cell and mesenchymal lesions - A study of 61 cases

BACKGROUND, Spindle cell and mesenchymal lesions of the lung encompass a wi de variety of benign and malignant conditions. However, to the authors' kno wledge, because of their rarity, few reports concerning their cytologic fin dings are available in the literature. The current review emphasizes the cy tomorphologic features, differential diagnosis, and potential pitfalls asso ciated with these lesions. METHODS. Seven hundred seventy-nine percutaneous lung fine-needle aspiratio n (FNA) specimens were retrieved from the authors' cytopathology files over a period of 5 years. Sixty-one cases (7.8%) in which a spindle cell compon ent was the dominant or key feature were identified. The authors reviewed t he cytologic smears, immunocytochemical studies, and corresponding surgical material and clinical information. RESULTS, Of these 61 aspirates, 33 (54%) were reactive processes (31 granul omas, 1 organizing pneumonia, and 1 inflammatory pseudotumor). Five cases ( 0.8%) were benign neoplasms (2 hamartomas, 2 solitary fibrous tumors, and 1 schwannoma). Twenty-three cases (38%) were malignant neoplasms (8 cases we re primary tumors [including 5 carcinomas with spindle cell or sarcomatoid features, 1 spindle cell carcinoid tumor, 1 leiomyosarcoma, and 1 synovial sarcoma] and 15 cases were secondary tumors [including 9 melanomas, 2 leiom yosarcomas, 1 malignant fibrous histiocytoma, 1 meningioma, 1 sarcomatoid r enal cell carcinoma, and 1 uterine malignant mixed mullerian tumor]). A spe cific diagnosis was rendered in 52 cases (85%). No false-positive cases wer e encountered but there was one false-negative case. One patient who was di agnosed with granulomatous inflammation on FNA was found to have nonsmall c ell lung carcinoma on subsequent transbronchial biopsy. No malignant cells were identified in the smears on review. The FNA from the organizing pneumo nia was interpreted as a solitary fibrous tumor whereas the inflammatory ps eudotumor was diagnosed as granulomatous inflammation. The FNA from one pul monary hamartoma initially was considered to be nondiagnostic. One solitary fibrous tumor and the schwannoma were diagnosed as smooth muscle tumor and spindle cell tumor, not otherwise specified, respectively. Among the malig nant tumors, the primary synovial sarcoma and one of the metastatic maligna nt melanomas initially were interpreted as primitive neuroectodermal tumor/ Ewing sarcoma and poorly differentiated carcinoma, respectively. CONCLUSIONS. Spindle cell lesions of the lung rarely are encountered on tra nsthoracic lung FNA and are comprised of a wide variety of benign and malig nant entities. By correlating clinical and radiologic data, cytologic findi ngs, and ancillary studies, a high diagnostic accuracy rate can be achieved with FNA. Cancer (Cancer Cytopathol) 2001;93:187-198. (C) 2001 American Ca ncer Society.