Do doctors see a lot of patients with spermatocele?

Yes. This is a pretty common concern because most of them are worried they have cancer when they find a lump in their groin or scrotum.
Yes. Urologists would consider it to be their "bread and butter.".
Here are some ... The exact incidence of spermatocele is unclear but spermatocele is present in some 25-30% of scrotal ultrasound study concerning scrotal pain, mass, or torsion, etc. So, it's common but usually asymptomatic.