Thymic neuroendocrine tumors (paraganglioma and carcinoid tumors): A comparative immunohistochemical study of 46 cases

Twenty-two paragangliomas from different anatomical sites and 24 thymic neuroendocrine carcinomas (carcinoid tumors) were analyzed for traditional and novel immunohistochemical markers. In the paraganglioma group, there were 8 men and 14 women between the ages of 23 and 79 years (mean, 46 years). Their symptoms depended on the location of the tumor and included neck swelling and Horner syndrome for neck tumors, whereas abdominal and chest pain was present in tumors of the abdomen and mediastinum, respectively. One patient had Carney triad. In the carcinoid group, the patients were 20 men and 4 women between the ages of 25 and 78 years (mean, 48 years). These patients were symptomatic with chest pain, shortness of breath, and dyspnea. One patient presented with multiple endocrine neoplasia syndrome. Complete surgical resection was accomplished in all patients. The 46 neuroendocrine tumors were evaluated for GATA-3, pancytokeratin, thryoid transcription factor 1 (TTF-1), napsin A, chromogranin A, and synaptophysin. All paragangliomas were universally positive for chromogranin A and synaptophysin, but negative for pancytokeratin, TTF-1, and napsin A. GATA-3 was expressed in 12 (55%) of 22 tumors. The thymic neuroendocrine carcinomas (carcinoid tumors) were universally positive for pancytokeratin, but negative for GATA-3 and napsin A. Chromogranin A and synaptophysin were expressed in 92% and 88% of cases, respectively, and TTF-1 in 4 (17%) of 24 cases. Based on these results, we recommend that the workup of neuroendocrine tumors should include not only the conventional neuroendocrine markers and pancytokeratin but also other markers such as GATA-3 and TTF-1 in order to arrive at a better interpretation.