Panniculitis (overview)M79.3

Polyaetiological, heterogeneous group of mostly localised, rarely generalised, inflammatory diseases of the adipose tissue (panniculus = lobules) in which a phasic, reactive inflammatory process takes place, which ends either in a restitutio ad integrum or in scarring defect healing (adipose tissue atrophy), recognisable by retracted defects of the skin surface.

There is no generally accepted classification of panniculitis, so all classificatory approaches have always been provisional.

For example, different names are used by clinicians and pathologists for the same clinical picture (erythema induratum vs nodular vasculitis).

Also, older terminology has become obsolete, such as " panniculitis nodularis nonsuppurativa febrilis et recidivans".

Based on new findings, it can be assumed that the term panniculitis nodularis nonsuppurativa febrilis et recidivans conceals several distinct clinical pictures, such as AAT deficiency-associated panniculitis, pancreatic panniculitis or lupus panniculitis. The present classification is based primarily on histological criteria (septal vs. lobular; with vasculitis vs. without vasculitis), and secondarily on etiological (traumatic, infectious, articular) criteria. However, it must be clarified that the subdivision into septal and lobular panniculitis is often difficult, since pure forms are rather rare and mixed pictures are the rule.

Lobular panniculitis*:

• Without vasculitis:
  • Panniculitis nodularis nonsuppurativa febrilis et recidivans (Pfeiffer-Weber-Christian syndrome)
  • Lipogranulomatosis subcutanea
  • Pancreatic panniculitis
  • Physical/traumatic/artificial panniculitis:
    • Cold panniculitis
    • Pressure panniculitis
    • Panniculitis after injections
    • Panniculitis due to artifacts
  • Panniculitis, with "needle shaped clefts" in lipocytes:
    • Sclerema adiposum neonatorum
    • Adiponecrosis subcutanea neonatorum
    • Panniculitis, post-steroidal
  • Lobular panniculitis in collagenoses:
    • Lupus panniculitis
    • Systemic scleroderma
    • Morphea
    • Panniculitis in dermatomyositis
  • Lobular panniculitis in other diseases:
    • Sarcoidosis
    • Granuloma anulare
    • Necrobiosis lipoidica
    • Panniculitisin chronic polyarthritis (rheumatoid arthritis)
    • Panniculitis calcificans (renal insufficiency)
    • Panniculitisin severe gout (gouty panniculitis)
    • Eosinophilic panniculitis
    • Neutrophilic p anniculitis (in myelodysplastic syndrome, Chen HC et al. 2004)
  • Panniculitis in malignant systemic diseases:
    • Panniculitic cutaneous T-cell lymphoma
    • Leukemias of the skin
    • Panniculitis, histiocytic, cytophagic.
  • Panniculitis due to infections:
    • Panniculitis, bacterial
    • Panniculitis, mycotic
• With vasculitis:
  • Erythema induratum Bazin (nodular vasculitis).

Septal panniculitis*:

• Without vasculitis:
  • Erythema nodosum
  • Necrobiosis lipoidica
  • Eosinophilic fasciitis
  • AAT deficiency-associated panniculitis
  • Dermatoliposclerosis
• With vasculitis:
  • Polyarteritis nodosa, systemic
  • Polyarteritis nodosa, cutaneous
  • Thrombophlebitis migrans

* Exclusively lobular or septal panniculitis are not observed. Thus, both terms should be understood as "predominantly septal" or "predominantly lobular".

See under the individual clinical pictures. The biopsy of an older panniculitis is worthless. To obtain representative material, a deep biopsy of a fresh lesion (first clinical manifestations) is required. In longer-standing panniculitis, resorptive inflammatory reparative processes override the initiating process. These reparative processes are largely identical histomorphologically for all forms of panniculitis and are therefore diagnostically inconclusive. The biopsy must be performed as a wide excision biopsy as "atraumatically" as possible and extend to the muscle fascia. Punch biopsies are not indicated because of the lack of depth of the excision.

1. Chen HC et al (2004) Neutrophilic panniculitis with myelodysplastic syndromes presenting as pustulosis: case report and review of the literature. Am J Hematol 76:61-65.
2. Ferrara G et al (2013) Panniculitis with vasculitis. G Ital Dermatol Venereol 148:387-394
3. Grassi S et al (2013) Panniculitis in children. G Ital Dermatol Venereol 148:371-385
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6. Patterson JW (2003) Panniculitis. In: Bologna JL et al (eds) Dermatology, Mosby London New York Toronto, pp 1551-1552.
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9. Xiao W et al (2021) Panniculitis caused by progesterone injection can be treated by physical therapy. Dermatol Ther 34:e14501.