Spindle-cell thymic carcinoid occurring in multiple endocrine neoplasia I: fine-needle aspiration findings in a case.

Thymic carcinoid tumors are important to distinguish from thymomas because of their worse prognosis. These rare tumors occasionally occur in the setting of multiple endocrine neoplasia (MEN). A needle biopsy was performed on a 57-yr-old woman with MEN I and a newly-discovered anterior mediastinal mass. Aspiration smears were cellular and contained polygonal-to-spindled cells with high nucleocytoplasmic ratios and evenly-dispersed pattern. Occasional nuclear molding and rosette-like arrangements were present. A synaptophysin immunostain was positive on cell-block preparation. A diagnosis of thymic carcinoid was made. Subsequent excision of the mass confirmed the diagnosis of thymic carcinoid. Thymic carcinoids are cytologically similar to carcinoid tumors elsewhere. They should be distinguished from epithelial thymoma and substernal medullary carcinoma of the thyroid.