Primary pulmonary leiomyosarcoma. Report of a case diagnosed by fine needle aspiration cytology

BACKGROUND: Primary pulmonary leiomyosarcoma is a rare but important entity. We report a case diagnosed by fine needle aspiration cytology. CASE: A 73-year-old male presented with an asymptomatic, right, pulmonary, subpleural nodule detected by computed tomography during follow-up for chronic obstructive pulmonary disease. Fine needle aspiration cytology showed cellular smears with numerous single or loosely cohesive groups of spindle-shaped to round cells. The tumor cell nuclei were blunt ended (cigar shaped), with fine to fine-granular chromatin, prominent nucleoli and an irregular nuclear rim. The tumor cells were positive for desmin and negative for cytokeratin and S-100 protein by immunocytochemistry. Right upper lobectomy with lymph node dissection was performed. Pathologic diagnosis after microscopic, immunohistochemical and electron microscopic studies was leiomyosarcoma. CONCLUSION: To our knowledge, this is the first reported case of primary pulmonary leiomyosarcoma arising in the subpleural region diagnosed by fine needle aspiration cytology. Immunocytochemistry was useful in establishing the diagnosis in this case.