obviously i cannot see the skin of your knuckle to offer you a patient specific answer (your description is really too vague) but i can tell you that contact (skin-to-skin) with a tumor would not transmit anything to you or your hands.
my knuckle touched a cancerous tumor. now the skin of that knuckle looks burnt & wrinkly. aging or result from contact? . i was helping my sister clean a cancerous tumor. the cleaning process started before we thought to put on gloves. i' be noticed over the past several months that the skin on that knuckle has a burnt wrinkly texture. not sure if my knuckle came in contact with the tumor or not but there was no problem with my skin until that incident. the area is more defined as time goes. it does not itch. could it just be that the skin is aging in that area. it is the skin over the 3rd knuckle.