Panniculitis

Panniculitis
Erythema induratum, a form of lobular panniculitis
Classification and external resources
Specialty	rheumatology
ICD-10	M79.3
ICD-9-CM	729.3
DiseasesDB	29081
MeSH	D015434
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Panniculitis is a group of diseases whose hallmark is inflammation of subcutaneous adipose tissue (the fatty layer under the skin - panniculus adiposus). Symptoms include tender skin nodules, and systemic signs such as weight loss and fatigue.

Restated, an inflammatory disorder primarily localized in the subcutaneous fat is termed a "panniculitis," a group of disorders that may be challenging both for the clinician and the dermatopathologist.

It can occur in any fatty tissue (cutaneous or visceral) and is often diagnosed on the basis of a deep skin biopsy, and can be further classified by histological characteristics based on the location of the inflammatory cells (within fatty lobules or in the septa which separate them) and on the presence or absence of vasculitis.

There are thus four main histological subtypes:

Erythema induratum, or "Bazin disease", is a panniculitis on the back of the calves. It was formerly thought to be a reaction to the tuberculum bacillus. It is now considered a panniculitis that is not associated with a single defined pathogen.

Nodular vasculitis is a skin condition characterized by small, tender, reddened nodules on the legs, mostly on the calves and shins. Microscopically there are epithelioid granulomas and vasculitis in the subcutaneous tissue, making it a form of panicullitis. Most of these cases are now thought to be manifestation of tuberculosis and indeed they respond well to anti-tuberculous treatment.

Non-vasculitis forms of panniculitis that may occur include:

Lipodermatosclerosis is a form of panniculitis associated with chronic venous insufficiency that presents with brown indurations on the front of the shins. It may be associated with pain and other signs of chronic venous insufficiency. The exact cause is unknown.

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