Sperm granuloma A sperm granuloma is a lump of sperm that can cause small bumps or cysts that range from 1 millimeter to 1 centimeter in size. A person can experience multiple lesions. They don’t usually cause any symptoms. However, some men may have pain at the granuloma areas.

Experts estimate 15 to 40 percent of men undergoing vasectomy experience a sperm granuloma. In some instances, a man may have to have the granuloma surgically removed.