Solitary fibrous tumor of the lung: a case report with a study of the aspiration biopsy, histopathology, immunohistochemistry, and autopsy findings.

Solitary fibrous tumor (SFT) is a rare mesenchymal neoplasm of ubiquitous location. In addition to its classic presentation as a pleural-based mass, it can be encountered in a variety of other sites. A pleural-based lung lesion can be easily accessed by radiologic guidance for cytologic study. Several reports have described the cytologic findings of SFT at various locations, including the lung. However, diagnostic difficulties can occur due to unusual clinical, radiologic, atypical cytomorphologic, and histologic features. We describe a case of intrapulmonary SFT in which a false-positive malignant diagnosis was rendered on fine-needle aspiration biopsy and concurrent surgical core biopsy prior to radiofrequency ablation. The patient died of procedural complications, and an autopsy was performed. Retrospective study of the case, especially correlation of cytologic, histologic, autopsy findings, and immunohistochemistry results were helpful in correctly diagnosing the case as SFT. We are reporting this case with emphasis on avoiding diagnostic pitfalls by being familiar with the accepted cytohistologic features and appropriate immunohistochemical results. (c) 2007 Wiley-Liss, Inc.