Disease causes difficult-to-diagnose rash

Dear Dr. Roach: My daughter was diagnosed with lymphomatoid papulosis. It’s not a bad case, but it’s enough to make me worry. I know it’s rare for this to turn into cancer, but there is always a chance. Doctors often misdiagnose it, but thankfully I have the best pathologist in the world. My daughter is being treated with UVB light, which worked in the past, but now is not helping. I don’t want to do methotrexate. I worry about every dot that pops up on her, and if it doesn’t go away, I think the worst. — M.W.M.

Answer: Lymphomatoid papulosis is a rare disease, most common in people in their 40s, but can happen in children and older adults as well. The cause is unknown, and although a virus is suspected, it hasn’t been found. It is not contagious.

The rash of LyP is not specific and needs to be confirmed through biopsy. Spots are relatively large (but less than an inch), and usually red but with a white center that can turn black. The rash comes and goes. A skilled pathologist in combination with an experienced dermatologist is necessary to make the diagnosis.