Primary diagnosis of malignant mesothelioma by fine-needle aspiration of a supraclavicular lymph node.

Malignant mesothelioma is a rare neoplasm with poor prognosis. The pleural form is defined as a malignant tumor of mesothelial cells with a diffuse growth pattern involving the visceral and parietal surfaces of the pleura. To our knowledge, there have only been two reported cases in the literature where fine-needle aspiration (FNA) of a lymph node was the primary mode of diagnosis of malignant mesothelioma. We describe a 40-yr-old male in whom the primary diagnosis of malignant mesothelioma was made by FNA of a supraclavicular lymph node. The mesothelial origin of the tumor was confirmed with immunohistochemical studies. A pleural biopsy immediately preceding the FNA was interpreted as chronic inflammation. Most patients with clinically documented lymph node metastases of malignant mesothelioma have had a previously established diagnosis of mesothelioma. Our case demonstrates that FNA can be a simple and invaluable method of diagnosis in those unusual cases where diagnosis of malignant mesothelioma has not already been made before lymphadenopathy.