Imaging findings of a primary bilateral testicular carcinoid tumor associated with carcinoid syndrome

A carcinoid tumor derived from neuroendocrine cells can release serotonin and other vasoactive substances into the systemic circulation, resulting in carcinoid syndrome, the manifestations of which are episodic flushing, wheezing, diarrhea, and eventual right-side valvular heart disease. Although 85% of carcinoid tumors occur in the appendix or ileocecal region, up to 15% occur in the lung, liver, or genitourinary tract. A carcinoid tumor is a rare testicular neoplasm, accounting for fewer than 1% of all testicular neoplasms.(1) We report a case of a primary bilateral testicular carcinoid tumor associated with carcinoid syndrome, which was shown as a hypervascular mass without calcification on sonography.