Unusual Shoulder Pain Leads to Rare Diagnosis

A young man, just 23 years old, went to the doctor because his left shoulder hurt. He was a police officer, so he thought maybe he had hurt himself on the job. The doctor thought it might be a common problem called rotator cuff impingement. But when the usual treatments didn't help, they took a closer look. They found something strange in his shoulder bone—a hole-like spot called a lytic lesion. A small piece of tissue was taken out for testing. The results showed something very rare: Rosai-Dorfman disease. This is a condition where certain immune cells, called histiocytes, grow too much and build up in different parts of the body. Normally, this disease affects the lymph nodes, causing them to swell up. But in this case, it was in the shoulder. The good news is that this disease often goes away on its own and isn't dangerous. But if it doesn't get better, treatment can be tailored to the person's needs. In this case, the young man got better without any treatment. He was able to go back to his normal activities. It's a reminder that even when something seems common, like shoulder pain, there can be rare and unexpected causes.