I have discomfort feeling in my left testicle. i've had a lump since i was little and doctor said that's it's nothing serious(10 years ago)is this ok?

Cyst of epididymis: otherwise known as a spermatocele is most common benign lump attached to testis. Management depends upon degree of discomfort & would include scrotal ultrasound followed by simple surgical excision if you prefer to have it treated rather than do nothing. Surgery, under general anesthesia, is minor, simple & straight forward, for a urologist,as scrotal wall is very thin.