“Sarcoidosis is a condition that causes tiny collections of immune system cells in any part of the body. These tiny collections form red, swollen lumps called granulomas. Granulomas most commonly occur in the lungs and the lymph nodes of the chest. They also can occur in the eyes, skin, heart and other organs.

Experts don’t know the exact cause of sarcoidosis, but it’s likely a mix of genetic and environmental factors. Some people appear to have gene changes that make them more likely to develop sarcoidosis. The condition may then be triggered by bacteria, viruses, dust or chemicals.”

MAYO CLINIC (Sarcoidosis – Symptoms and causes – Mayo Clinic)