Primary malignant carcinoid of the testis.

A primary malignant carcinoid in the testis of a 76-year-old man was studied. The clinical indication was the appearance of extensive, papular cutaneous metastases. A markedly enlarged, indurated left testis was discovered during evaluation of the skin lesions. There were no clinical features of carcinoid syndrome. Histochemically, the tumor cells were argyrophilic but nonreactive to an argentaffin stain. Electron microscopy revealed numerous round, neurosecretory-type granules that ranged from 70 to 300 nm. At the time of autopsy, metastases were found in the heart, lungs, and the opposite testis. Review of the laterature failed to uncover any previous reports of a primary malignant carcinoid in the testis.