It's just the lack of treatment seems odd. Apparently mine doesn't look too classical, as when I saw a rheumatologist because I was concerned about psoriatic arthritis he hadn't seen anything similar before. I never had a biopsy, the dermatologist looked at it, diagnosed it and gave me samples of the prescription. Luckily, the GP that time got on the phone right when I was there and called to see if there was a cancellation, partially I think because it would flare and disappear and it needed to be there are the time. It was also having a negative impact on my overall health, as I was dealing with the neurological problems and chronic fatigue and moving onto the affected areas would wake me up when I was sleeping. I got in within a week.
The last time I saw a dermatologist it was more of a typical wait time. He took a swab, but wrote a prescription that wouldn't help if the test came back positive. I usually find dermatologists want to give something that will hopefully help, and if tests say otherwise, then they will change the treatment.