Skin inflammatory (nontumor)
Panniculitis
General


Topic Completed: 1 August 2011

Revised: 2 April 2019

Copyright: 2002-2019, PathologyOutlines.com, Inc.

PubMed Search: Panniculitis [title] skin

Mowafak Hamodat, M.B.Ch.B., M.Sc.
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Cite this page: Hamodat M Panniculitis. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/skinnontumorpanniculitis.html. Accessed August 19th, 2019.
Definition / general
  • Inflammation of subcutaneous fat affecting connective tissue septa separating lobules, usually in lower legs
  • Poorly defined, tender, erythematous nodules
  • Variable fever, malaise
  • Lesions are transient
  • Either septal (involving fibrous septa) or lobular (involving lipocyte lobules)
  • Inadequate biopsy specimens, particularly punch biopsies, may include no subcutaneous fat, and make diagnosis difficult if not impossible

  • Lobular panniculitis: due to nodular vasculitis (erythema induratum), subcutaneous fat necrosis of newborn, pancreatic fat necrosis, lupus panniculitis, physical and factitious panniculitis, other
  • Lupus panniculitis: also called lupus profundus; may develop in normal skin or preexisting skin lesion of patient with systemic or discoid lupus erythematosus
  • Physical and factitious panniculitis: due to blunt force, pinching, cold or injection of foreign substances for secondary gain; a diagnosis of exclusion
  • Septal panniculitis: due to erythema nodosum or alpha-1-antitrypsin deficiency
Case reports
Microscopic (histologic) description
  • Lupus panniculitis: vacuolar interface change and lymphoid infiltrates in dermis in lupus-related lesions; in non lupus-related skin lesions, see ghost cells due to loss of nuclei and basophilic material replacing cell membranes, causing basophilic sclerosis of lobules; dense lymphoplasmacytic infiltrates in lobules and septa; variable dermal and septal mucin; fibrosis over time
  • Septal panniculitis: lobular neutrophils, variable focal fat necrosis; refractile material may be present if substances were injected
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