@mburg2 - I think the doctor takes a small biopsy of your skin in the affected area. Here's what the National Organization for Rare Disorders says - "Grover's disease is a rare, transient skin disorder that consists of small, firm, raised red lesions, most often on the skin of the chest and back. Diagnosis of this disorder becomes apparent under microscopic examination when the loss of the “cement” that holds the skin cells together is observed." -- Grover's Disease: https://rarediseases.org/rare-diseases/grovers-disease/

Have you discussed it with your doctor?

I had a “punch biopsy”.