Primary carcinoid tumor of the bilateral testis associated with carcinoid syndrome

Carcinoid tumors derived from neuroendocrine cells can release serotonin and other vasoactive substances into the systemic circulation, resulting in carcinoid syndrome. Testicular carcinoid, a rare disease accounting for less than 1% of all testicular neoplasms, rarely manifests symptoms of carcinoid syndrome. We describe a case of carcinoid syndrome arising from a primary testicular carcinoid tumor. A 21‐year‐old male patient presented with facial flushing and diarrhea for 5 years. He had an enlarged left testis and a 1‐cm, ill‐defined, hard, non‐tender mass in his right testis. His 24 h urinary excretion of 5‐hydroxyindoleacetic acid was elevated (16.1 mg/day). Somatostatin receptor scintigraphy correlated with carcinoid tumor in both testes. Following bilateral orchiectomy, the patient's facial flushing and diarrhea disappeared.