THYMIC CARCINOID - REPORT OF A CASE WITH DIAGNOSIS BY FINE-NEEDLE ASPIRATION BIOPSY

BACKGROUND: Fine needle aspiration biopsy (FNAB) affords a less expens ive, less morbid approach to masses within the complex anatomy of the mediastinum as opposed to surgical biopsy. Given the current state of computed tomography guidance and the available cell block preparations and ancillary studies, definitive diagnosis of mediastinal tumors is possible. CASE: A 19-year-old male presented with weight loss and musc le weakness. Computed tomography revealed an anterior superior mediast inal mass with attachment to the posterior sternum and anterior aorta. FNAB yielded hyperchromatic cells with densely clumped chromatin and prominent nucleoli. These were present as single cells and clusters. C ell block preparations were studied with immunoperoxidase methods and were strongly positive for chromogranin and glucagon, supporting the d iagnosis of carcinoid tumor. Surgical excision yielded a 7-cm, unencap sulated, red-brown tumor with medium-sized cells with oval to round nu clei, scant and granular cytoplasm and coarse ''salt and pepper'' chro matin with prominent nucleoli. The cells were arranged in islands and bands and were associated with;prominent capillaries and dense, collag enous septae. Immunoperoxidase and electron microscopy demonstrated nu merous intracytoplasmic, nonspecific neurosecretory granules and posit ivity for somatostatin, synaptophysin, cytokeratin and chromogranin. C ONCLUSION: FNAB affords an accurate and timely diagnosis of an anterio r mediastinal tumor without the necessity for open biopsy and also off ers accurate surgical planning and decreased morbidity.