Have you ever had the lesions on your scalp biopsies? I had a very itchy rash in the area under my breasts that would flare and subside for 3-4 years and was treated for bacterial infection and for fungal infection when I had my annual dermatology exam at Mayo Clinic. In 2016, I had a punch biopsy of similar rash in my groin area and was diagnosed with a rare disease, Langerhans cell histiocytosis. It is a blood disease that is primarily a pediatric disease, but can affect one at any age. It causes most frequently causes skin lesions and/or lesions on bones. It can also appear in lungs,spleen, liver, or on pituitary gland. It can only be diagnosed by biopsy of lesions and requires special staining by pathologist to identify. It is seen so rarely that most doctors never see an adult with it and never think to check for it. I was treated with many topicals, including strong steroidal ointments, Valchlor gel and even brachytherapy. All irritated my skin and only when I started on Hydrea in late 2019 did it get better. It took several months to end the sometimes ulcerative rash. the raw skin with weeping. I now have some areas of small red bumps that occasionally itch, especially at night, but has been like a miracle. I also was diagnosed in 2019 with chronic myelomonocytic leukemia. There may or may not be a connection, such both are myeloid diseases.
I realize that this would be a long shot, but I feel that LCH is under diagnosed and most adults are not diagnosed for months or even years after lesions first appear.