Go through these in order and stop at the first one that applies. If you are reading this for someone else, answer for them.
Get urgent or emergency help for sudden, severe testicular pain, especially with swelling, nausea, or vomiting.
This can be testicular torsion, in which the testicle twists and loses its blood supply.
Torsion is not a typical sign of a Leydig cell tumor, but it needs treatment within hours.
Arrange a prompt medical appointment if you notice a new testicular lump, persistent swelling, a change in testicle size or firmness, or a heavy feeling in the scrotum.
These symptoms have several possible causes, many of which are not cancer, but they should be examined.
After surgery, seek urgent advice for rapidly increasing swelling, heavy bleeding, worsening redness, pus, fever, severe pain, chest pain, or difficulty breathing.
Also seek routine medical assessment for unexplained breast growth, ongoing sexual or fertility changes, or signs of unusually early puberty in a child.
Every sign above is quoted from the sofidex article on Leydig cell testicular tumor. If you are not sure, err upward — it is always reasonable to be checked.