Agree with Blu and Karla. Always best to have things checked and the sooner the better.
You should take him to see the vet. You are right to avoid touching something when you don't know what it is. Request a fine-needle aspiration be done, and if that shows nothing, request a biopsy to be sent off and checked for cancerous cells. Only after these things are done should you consider any sort of surgery be done to remove it. Blessings - Blu
Welcome to the forum.....ALL Lumps and Bumps should be examined by your Vet....If it's something serious, the sooner it's caught, the better......There are many kinds of growths that develop on dogs.....It doesn't have to be Cancer......Get your guy to his Vet ASAP to have it examined...Good luck & let us know what you find out....Karla