What could possibly be when i find lumps under testicle in scrotum when im masturbating and about to ejaculate? they are painless lumps and they disappeared after i ejaculated. i could only feel the hard lumps when im masturbating and ejaculate.

Engorged Epididymes: No concern for cancer. Cancerous lumps are hard & do not disappear without being surgical removed. Tail of epididymis is usually locatedon underside of testis, although in your case might be head of epididymis which can feel like a lumo, especially when engorged.

Please see a Urologist Doctor with expertise in male reproductive organs for a thorough evaluation and recommendations.