Diagnosis
An infection of fat.
Epidemiologic Risks
It can be post-op, by direct inoculation or hematogenously. I have seen a pair of spontaneous cases.
More often non-infectious: lupus erythematosus or scleroderma, lymphoma or histiocytosis, sarcoidosis with cutaneous involvement, Alpha 1-antitrypsin deficiency. Pancreatitis as lipase eats adipose. And acinar cell carcinoma of the pancreas causes necrotizing panniculitis.
microbiology
Anything. So get a culture.
Empiric Therapy
Depends on the risks etc.
Pearls
I see most of the cases after abdominal surgery in the morbidly obese. Abdominal wall fat is remarkably poorly vascularized and many antibiotics have poor penetration into adipose.
Infections of large hanging abdominal pannuses are particularly hard to treat as impossible to elevate and the inflammation pools in dependent areas.
The plural is Panniculitides, which sounds like a constellation of some sort.
Curious Cases
Relevant links to my Medscape blog
Last Update: 12/11/18.