Skin nontumor
Panniculitis
Lupus erythematosus panniculitis (LEP)

Author: Robert E. LeBlanc, M.D. (see Authors page)

Revised: 8 August 2017, last major update August 2017

Copyright: (c) 2002-2017, PathologyOutlines.com, Inc.

PubMed Search: (Lupus erythematosus panniculitis) LEP

Cite this page: Lupus erythematosus panniculitis. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/skinnontumorlupuschronic.html. Accessed September 24th, 2017.
Definition / general
Essential features
  • Tender subcutaneous plaques and nodules
  • Autoimmune lobular lymphocytic panniculitis
  • Patients often do not have or develop systemic lupus
  • Must be distinguished from subcutaneous panniculitis-like T cell lymphoma
  • Presence of high Ki67 or hotspots favors a diagnosis of subcutaneous panniculitis-like T cell lymphoma (SPTCL)
  • Patients with overlapping lupus erythematosus panniculitis and SPTCL features may develop hemophagocytic lymphohistiocytosis (HLH)
Terminology
  • Lupus panniculitis
  • Lupus erythematosus profundus (when there is concomitant discoid lupus erythematosus)
ICD-10 coding
  • L93.2
Epidemiology
  • Women more often than men
  • Usually young to middle aged adults
  • Fewer reported cases in childhood and in patients of advanced age
  • Rare manifestation of autoimmune connective tissue disease, representing less than 3% of patients with cutaneous or systemic lupus erythematosus
Sites
  • Trunk, breast, proximal extremities (upper more often than lower), face and scalp
  • Distal extremities are less commonly involved
Clinical features
  • Tender, indurated and erythematous plaques and nodules
  • Overlying skin occasionally shows features of discoid lupus (scaling, plugged follicles, scarring and atrophy)
  • Lesions may spontaneously regress and recur
  • Occasional severe lipoatrophy with resolution of lesions
  • Patients often do not have a history of cutaneous or systemic lupus
  • Some patients develop mild systemic symptoms but do not meet full criteria for a diagnosis of systemic lupus
Laboratory
  • Antinuclear antibodies are identified in a subset of patients with LEP
  • The absence of antinuclear antibodies does not exclude LEP
Case reports
Treatment
  • Antimalarial agents
  • Topical corticosteroids for concomitant discoid lupus
  • Systemic corticosteroids and other immunosuppressants are sometimes used temporarily at disease onset
Microscopic (histologic) description
  • Lobular or mixed lobular and septal panniculitis
  • Hyaline lipomembranous changes punctuated by foci of active lobular panniculitis
  • Infiltrate consists of lymphocytes, histiocytes and plasma cells
  • Germinal center lymphoid follicles present throughout the lesion
  • Plasma cells may be prominent and form large clusters
  • Lymphocytes are small, bland and splay apart adipocyte lobules
  • Lymphocytic vasculitis, granulomas and dermal mucin are variable
  • Features of discoid lupus are present in a subset of patients (this is termed lupus erythematosus profundus)
Microscopic (histologic) images

Images hosted on PathOut server:

Images contributed by Robert E. LeBlanc M.D.

H&E (10x, 20x, 40x)

CD4, CD8, Ki67

Positive stains
  • CD123 highlights clusters of plasmacytoid dendritic cells
  • CD4 highlights a majority of the lymphocytes in the fat
Negative stains
  • Ki67 is generally very low with no foci of increased staining
  • CD8 should not highlight a preponderance of the lymphocytes
Differential diagnosis
  • Injection site reaction or drug reaction: this distinction relies heavily on clinical correlation
  • Other connective tissue disease associated panniculitidies: this distinction relies heavily on clinical correlation
  • Subcutaneous panniculitis-like T cell lymphoma:
    • Ki67 is either expressed diffusely throughout the lesion or in hotspots enriched with adipotropic cytotoxic CD8+ T cells
    • The lymphoma cells are slightly enlarged and hyperchromatic with irregular nuclear contours
    • They surround individual fat lobules but also appear within the disrupted cell membranes of involved adipocytes
    • Paired T cell gene rearrangement studies may be helpful to assess clonality
Board review question #1
Subcutaneous panniculitis-like T cell lymphoma is characterized by which of the following immunophenotypes?

  1. CD4+ T cells, high Ki67 expression
  2. CD4+ T cells, low Ki67 expression
  3. CD8+ T cells, high Ki67 expression
  4. CD8+ T cells, low Ki67 expression
Board review answer #1
C. SPTCL has a cytotoxic CD8 possitive immunophenotype and high expression of Ki67 that can often permit its distinction from lupus erythematosus panniculitis.
Board review question #2
Which of the following microscopic findings would favor the diagnosis of lupus erythematosus profundus over lupus erythematosus panniculitis?

  1. Epidermal vacuolar interface changes
  2. Hyaline lipomembranous changes
  3. Lobular lymphohistiocytic panniculitis
  4. Lymphocytic vasculitis
Board review answer #2
A. Lupus erythematosus profundus is the preferred terminology for lesions of lupus erythematosus panniculitis that have overlying changes of discoid lupus, namely vacuolar interface dermatitis, basement membrane thickening, scale, follicular plugging and both perifollicular and periadnexal inflammation. The other answer options can be present in both lupus erythematosus profundus and lupus erythematosus panniculitis.