Duodenal carcinoid tumor: Report of a case diagnosed by endoscopic ultrasound-guided fine-needle aspiration biopsy with immunocytochemical correlation

Fine-needle aspiration biopsy is a reliable and accurate method for the end oscopic diagnosis of gastrointestinal malignancies and it is particularly w ell suited for evaluation of submucosal lesions. We report the cytopatholog ic findings of a case of malignant carcinoid tumor of a 44-year-old male wh o presented with melena and a nonhealing duodenal ulcer. Endoscopic ultraso und examination revealed a submucosal lesion in the pyloric region. Fine-ne edle aspiration revealed abundant cellularity with tumor cells arranged in sheets and loose groups and dispersed single cells in a clean background Pa pillary fragments, capillaries cuffed by tumor cells, and rosette formation were also noted. The cells were moderate in size, round to oval, with a sm all subpopulation of spindle-shaped cells. The nuclei were uniform, round t o oval, with smooth nuclear borders. The chromatin pattern was finely granu lar with a salt-and-pepper appearance. The cytoplasm of the cells was small to moderate in amount, pale, and showed fine granularity. The differential diagnosis included a neuroendocrine neoplasm vs. an epithelioid gastrointe stinal stromal tumor The tumor cells were focally positive for chromogranin and negative for CD34, supporting the diagnosis of a neuroendocrine neopla sm. The differential diagnosis of primary gastrointestinal carcinoid tumors from gastrointestinal stromal tumors can be very difficult in cytologic ma terial. In cases when diagnostic material is scant. or only present on one smear, the use of smear division and cell transfer in order to perform immu nocytochemical stains may be of considerable value to confirm the neuroendo crine nature of the neoplasms. (C) 2000 Wiley-Liss, Inc.