Classification It can occur in any fatty tissue (
cutaneous or visceral) and is often diagnosed based on 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 panniculitis without vasculitis (acute panniculitis, previously termed
Weber–Christian disease, systemic nodular panniculitis) • lobular panniculitis with vasculitis • septal panniculitis without vasculitis • septal panniculitis with vasculitis
Lobular With vasculitis 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 panniculitis. Most of these cases are now thought to be manifestations of tuberculosis, and indeed they respond well to anti-tuberculous treatment.
Without vasculitis Non-vasculitis forms of panniculitis that may occur include: •
Cytophagic histiocytic panniculitis 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 panniculitis with multisystem involvement. But it can also present in a benign form involving only the subcutaneous tissue, thus having a broad clinical spectrum. •
Traumatic panniculitis is a panniculitis that occurs following trauma to the skin. •
Cold panniculitis is a panniculitis occurring after exposure to cold, most often seen in infants and young children. •
Gouty panniculitis is a panniculitis caused by deposition of
uric acid crystals in
gout. Other forms include: •
Subcutaneous fat necrosis of the newborn, a form of panniculitis occurring in
newborns that is usually self-resolving, that may be a result of
hypoxic injury to relatively high levels of
brown fat.
Septal Erythema nodosum Erythema nodosum is a form of panniculitis 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 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 panniculitis is a panniculitis associated with a deficiency of the α1-antitrypsin enzyme inhibitor. ==See also==