Only a possiblilty...run a search on board and/or the net for lymphocytis (-us?) or cauliflower disease.
Not sure...one of the pic's appears kinda fuzzy, which this shouldn't I don't think. From what I understand, it should look more like a cluster of warts. It's a virus. No proven treatmt...you may find a couple of suggestions if you look around, but nothing certain. From what I remember reading, the lumps may go away, or they may stay and the fish might live with it for a long time. Quarantine suggested. And clean water.
My pleco had what looked like a cluster of three warts, and the largest started to turn reddish. Not in the form of a line tho, like yours...perhaps that might signify something else.
At any rate, I transferred him to a tank where the levels could be better maintained...not sure if I added Melafix at this time, think so tho. After a time, I checked him and saw that it appeared that it had fallen off, and he had a chunk missing from him, like a small gouge. continued/started Melafix at this time. It now appears to be gone. Can't say for sure that's what it was, but it's my closest guess.
hth