A set of three siblings came to me with indentations on their left upper arms (at the point where the deltoid muscle inserts into the humerus). The problem first started with the small girl. It began as an area of depigmentation 2 months prior to presentation. It progressed into a severe indentation overlying the deltoid muscle – almost like the muscle had atrophied (or withered away). I could feel the bone under the skin. She had no muscular weakness and no open wound. It was not painful nor tender. There was no associated itching. There was no history of a recent illness, an injection, insect bites nor trauma on the left arms.

The middle brother had the same process over one month duration. The oldest brother just had hypopigmentation over a span of 2 weeks without significant indentation. There was no other known family history. The children all sleep in the same bed (not an old mattress) under a mosquito net. There was no evidence of insects in their bed.
All the children had the BCG injection as babies, but those are routinely given in the right deltoid in Ghana (and the scars were readily visible on the children’s right shoulders.) All the lab work checked out fine. X-rays showed no bony involvement.
I sent the story and the photo to pediatricians in the USA who also sent the query to other experts. While possible diagnoses like atrophoderma of Perini and Pasini (associated with tick-borne disease), localized morphea, and possibly results of schlerotherapy by a traditional healer (although denied by the family) were proposed, no conclusive diagnosis was found.
Over the course of a month, the children were brought back for follow up. The lesions were static and not progressing. I weighed my options to biopsy, to treat with antibiotics for possible infections or to manage conservatively without any intervention. The children were not actively ill. They had full use of their arms and the lesions had stopped progressing.
I gave the mother instructions to return if she noticed any further changes which might necessitate biopsy and further investigation. In the end, I decided that the principle of “first do no harm” was the best guide in this situation.