Primary carcinoid tumor of the testis: case report.

Carcinoid tumor of the testis is exceedingly rare. Most carcinoid tumors occur in the appendix or ileocecal region (85%), while others are found in the lung, liver, and genitourinary tract (15%). A primary carcinoid testis tumor may originate from argentaffin or Kulchitsky's cells, which are located in the Lieberkuhn crypt. Preoperative ultrasound may show a solid, hypoechoic, well-defined margin mass combined with calcification or a cyst. Differential diagnosis of the ultrasound appearance is testicular tumor (teratoma/embryonal cell carcinoma), epidermoid tumor, tuberculous epididymo-orchitis, and the result of trauma. Radical orchiectomy remains the main treatment for a carcinoid testis tumor. Grossly, surgical removal of the tumor presents with a solid mass, tan to white in color. Immunohistochemical study shows that tumor cells are diffusely reactive to antibodies to keratins AE1 and AE3, chromogranin-A, neuron-specific enolase (NSE), and synaptophysin. A pure primary testicular carcinoid tumor has been treated as a benign lesion, while metastatic carcinoid tumor has a poor prognosis regardless of the primary site. To rule out the possibility of metastasis resulting from an extra-testicular primary carcinoid, careful and thorough postoperative whole body surveys are important. Chest X-ray, chest computed tomogram (CT), abdominal and pelvic CT, and octreotide scintigraphy are indicated. We herein describe a case of primary carcinoid tumor of the testis and review the literature.