We just went through this and had a biopsy done. The lab results came back "Vasculitis".
We had a lot of extenuating circumstances........brought home a foster puppy from the shelter with ringworm. She had 6 lesions, 5 of them pink, hairless, the size of a dime. But she also had one black scabby spot on one ear. She was treated with topical med and medicated shampoo and has gone on to her forever home.
Shortly after she left, Mack got very sick with a high temp (105*) and a large swelling on one side of his neck. The emergency vet suspected an infected and/or impacted salivary gland.
Mack was on Clavamox, continued to run low to med temps and felt bad. He was lethargic and had to be coaxed to eat.
It took about two weeks and he finally felt better when he broke out with a scab on the inside of one ear tip...it got worse and appeared on the outside as well. Then he got a smaller one on the OTHER ear tip.
I could find nothing that said ringworm looked like that....but DID find a lot of references to sarcoptic mange - with lesions on the ear tips being very symptomatic. I was convinced that was what we were dealing with......The vet said it would have been very itchy if it was sacoptic mange (and the ears were not itchy, but very painful).
As I said, the diagnosis was vasculitis.....but that is more of a symptom of something else going on. He's fine now, with no reoccurence of the lesions.