Basal cell skin cancer

Question
I had a cyst removed from my 5yr. old Labradors shoulder area and the biopsy came back maglignant basal cell skin cancer. Now he has formed a hard mass around his shoulder and neck. I took him back to the Vet. and he wasn't sure what was causing it and put him on antibiotics which are not working, since my Vet is not familiar with this I was wondering if you might have heard of anything similar to this, my only options now are to have expensive test done or possibly put him to sleep if it gets worse, I would appreciate any suggestions.

Answer
Most basal cell tumpor are benign, but occasionally there will be a carcinoma.  These can extend deep into the tissues, so if the first surgery left some of the deeper tissues seeded with cancer, then the solution is to to a very wide excision.  If it is on the shoulder, then limb amputation may be the only answer.  There are few chemotherapies available for Basal Cell Carcinomas.  Radiation may help the superficial ones, but not deep tumors.