Hi,
A PSA (Prostate Specific Antigen) of 4.0 in a 59 year old man with an enlarged prostate is not unduly worrying.
However, the lump in his armpit needs urgent evaluation. He should see a doctor and get an FNAC (fine needle aspiration cytology) of the lump done.
Just to let you know, it is unlikely for prostate cancer to spread to armpit and to cause a swollen neck/face. Prostate cancer would more likely spread to bones (especially the spine), liver etc.