The Role of Fine Needle Aspiration Cytology in the Diagnosis and Management of Thymic Neoplasia

Background:Fine needle aspiration biopsy is commonly used to document the metastasis to the mediastinum. It is less often used to make the primary diagnosis of tumors, particularly thymic neoplasms. This is due to fear of sampling error, rarity of thymic tumors, multiplicity of lesions in the mediastinum, and inexperience on the part of the cytopathologist. We show that needle aspiration sampling of thymic tumors, both thymoma and thymic carcinoma, is an accurate method of diagnosis.Methods and Results:In our series of 22 thymic tumors aspirated preoperatively and compared with the subsequent surgical resection, the accuracy of a diagnosis of thymoma was 100%, and the accuracy of a diagnosis of carcinoma was 100%. Difficulties were encountered when vague terminology was used, and insufficient information was conveyed. Immunohistochemical stains can be applied to cytologic material to aid in the identification of the epithelial and lymphocytic components of thymoma.Discussion:Correlation with clinical and radiographic information is necessary, and wording of the cytology report should be as complete and clear as possible.