Classification 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: # lobular<unk>  without vasculitis (acute<unk> , previously termed Weber–Christian disease, systemic nodular<unk>  # lobular<unk>  with vasculitis # septal<unk>  without vasculitis # septal<unk>  with vasculitis Lobular With vasculitis Erythema induratum, or "Bazin disease", is a<unk>  on the back of the calves. It was formerly thought to be a reaction to the tuberculum bacillus. It is now considered a<unk>  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<unk> . Most of these cases are now thought to be manifestation of tuberculosis and indeed they respond well to anti-tuberculous treatment. Without vasculitis Non-vasculitis forms of<unk>  that may occur include: * Cytophagic histiocytic<unk>  was first described in 1980 by Winkelmann as a chronic histiocytic disease of the subcutaneous adipose tissue, which is characterized clinically by tender erythematous nodules, recurrent high fever, malaise, jaundice, organomegaly, serosal effusions, pancytopenia, hepatic dysfunction and coagulation abnormalities. CHP may occur either isolated or as part of cutaneous manifestations of hemophagocytic syndrome (HPS). CHP is a rare and often fatal form of<unk>  with multisystem involvement. But it can also present in a benign form involving only the subcutaneous tissue, thus having a broad clinical spectrum. * Traumatic<unk>  is a<unk>  that occurs following trauma to the skin. * Cold<unk>  is a<unk>  occurring after exposure to cold, most often seen in infants and young children. This condition has been described in children who suck ice or popsicles, and therefore is sometimes referred to as "popsicle<unk> ." The term was coined when a patient with a rash of unknown origin on her cheek was taken to a dermatologist. * Gouty<unk>  is a<unk>  caused by deposition of uric acid crystals in gout. * Pancreatic<unk>  (also known as enzymatic<unk> , Pancreatic fat necrosis, and subcutaneous fat necrosis) is a<unk>  most commonly associated with pancreatic carcinoma, and more rarely with anatomic pancreatic abnormalities, pseudocysts, or drug-induced pancreatitis. * Factitial<unk>  is a<unk>  that may be induced by the injection of organic materials, povidone, feces, saliva, vaginal fluid, and oils. With needle-shaped clefts Lipodermatosclerosis is a form of<unk>  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. Other forms include: * Subcutaneous fat necrosis of the newborn, a form of<unk>  occurring in newborns that is usually self-resolving, that may be a result of hypoxic injury to relatively high levels of brown fat. * Sclerema neonatorum, affecting premature births. * Weber–Christian disease, a symmetrical form of the disease of unknown origin occurring in middle-aged women. * Lupus erythematosus<unk> ,<unk>  associated with lupus erythematosus. * Forms associated with use of high doses of systemic corticosteroids during rapid corticosteroid withdrawal, and from the injection of silicone or mineral oils. Septal Erythema nodosum Erythema nodosum is a form of<unk>  characterised by tender red nodules, 1–10 cm, associated with systemic symptoms including fever, malaise, and joint pain. Nodules may become bluish-purple, yellowing, and green, and subside over a period of 2–6 weeks without ulcerating or scarring. Erythema nodosum is associated with infections, including Hepatitis C, EBV and tuberculosis, Crohn's disease and sarcoidosis, pregnancy, medications including sulfonamides, and some cancers, including Non-Hodgkin lymphoma and pancreatic cancer. A1AT-deficiency-associated Alpha-1 antitrypsin deficiency<unk>  is a<unk>  associated with a deficiency of the α1-antitrypsin enzyme.
Panniculitis
Dactylitis
Trombiculosis
Cheilitis
Coxalgia
Palindromic rheumatism
Arthus reaction
Ankle flare