(BMJ)—An 11-yo boy presented w/ pigmented lesions on his back that had been slowly enlarging since he was 5 yo. Exam: thin build. Skin: 3 round, brown, hyperpigmented patches over the lower back, in the midline, above the bony protuberances; skin otherwise normal. What’s the dx?
Erythema dyschromicum perstans
Davener’s dermatosis
Acquired nevus of Ota
Berloque dermatitis
Lichen planus pigmentosus
You are correct. Further hx revealed he’d been constantly rubbing his back against the backs of chairs since he was younger. Davener’s is a form of frictional melanosis, caused by prolonged mechanical friction, pressure, or chronic irritation. There’s no age, gender, or ethnic predilection, and it can develop on any part of the body. Tx is usually conservative. If davener’s is detected early, stopping the friction may allow clearing to occur over many months. The pt’s parents were reassured that no further tx was required.

Archives of Disease in Childhood 2019;104:1137