CYTOLOGIC PATTERNS OF METASTATIC THYMOMA - DIAGNOSIS BY FINE-NEEDLE ASPIRATION BIOPSY

Thymomas are the most frequent primary tumors of the anterior mediasti num. These lesions are slow growing and can be locally invasive, but e xtrathoracic metastases are rare, occurring in less than 2% of cases. Fine-needle aspiration biopsy (FNAB) may be helpful in making the diag nosis of metastatic thymoma, with or without a clinical history of pri mary mediastinal thymoma. We report three cases of metastatic thymoma diagnosed by FNAB. Each case illustrates a distinctive cytologic patte rn. While two of the patients had a history of histologically confirme d thymoma 11 and 13 years previously, a third patient presented with a n enlarged supraclavicular lymph node and pulmonary nodules, and no pr ior diagnosis of thymoma. These cases demonstrate that based on distin ctive cytologic patterns and features, a diagnosis of metastatic thymo ma can be made with FNAB. Ancillary studies will often confirm the dia gnosis. (C) 1994 Wiley-Liss, Inc.