Factitial panniculitis.

Factitial panniculitides are subcutaneous tissue injuries produced by external agents or actions. In most cases, factitial panniculitis is caused by self-injection of different substances. Factitial panniculitis can also appear as an iatrogenic consequence of injections of drugs or immunization agents. The clinical features of factitial panniculitis are quite variable, depending on the inciting agent. The histopathology of factitial panniculitis usually shows a pattern of an acute lobular panniculitis associated with fat necrosis and an abundant inflammatory infiltrate predominantly composed of neutrophils.