Subcutaneous sarcoidosis with extensive caseation necrosis

We report a 24-year-old male patient with sarcoidosis who developed subcutaneous nodules on his thighs and buttocks at the sites of repeated intramuscular injections. Histologically, there were extensive areas of caseation necrosis surrounded by typical sarcoidal granuloma. The nodules regressed spontaneously over a period of 4 months, concurrently, both his bilateral hilar adenopathy and the results of immunological tests, returned to normal. We think that these lesions developed at the sites of subcutaneous scar tissue induced by frequent injections in childhood. We believe the pathomechanism to be similar to that for scar sarcoidosis, and that the extensive caseation necrosis reflected a regressing stage of the disease.