Case 241 - Discussion

Uploaded: 2008-06-04, Updated: 2008-06-04

Diagnosis: Granuloma Annulare

Palisaded Granulomatous Dermatitis

Granuloma Annulare (GA)

  • General: benign inflammatory, self-limiting granulomatous dermatoses;

  • Etiology: unknown;

  • Age and gender: both adults and children, female>male;

  • Location: hand, feet, arms and legs;

  • Gross: erythematous or flesh-colored discrete and coalescent papules in annular configurations

  • Histology:

    • Interstitial or Incomplete GA

      • Early interstitial pattern, lack typical palisading granulomatous dermatitis;
      • Macrophages and lymphocytes splay between individual collagen bundles;
      • Increased connective tissue mucin deposition with little or no collagen degeneration.
    • Palisaded GA
      • Fully developed, with palisaded granulomatous dermatitis;
      • Central necrobiosis: acellular areas with degenerated thinned collagen bundles, sometimes pale homogeneous light-blue appearance due to the presence of mucin;
      • Fibrohistiocytes and spindle cells radiate around the necrobiosis;
      • Central connective tissue mucin: colloidal iron, Alcian blue, ABPAS.
      • Away from the central palisade, there is superficial and deep perivascular inflammation with lymphocytes and macrophages, eosinophils commonly seen, no plasma cells.
    • Deep GA
      • Subcutaneous form, mostly in children, also called pseudo-rheumatoid nodule or nodular GA;

      • On the extensor aspects of hands, feet, lower legs, buttocks, scalp and periorbit;

      • Deeply eosinophilic centers of granulomas contain degenerated, homogeneous-appearing collagen.

Necrobiosis Lipoidica (Necrobiosis Lipoidica Diabeticorum, NLD)

  • General: 1/3 NLD have diabetes, <1% diabetic patients have NLD;
  • Age and Gender: adult, female > male;
  • Location: most commonly on the anterior shin;
  • Gross: waxy, indurated, yellow-brown patches or plaques with a surrounding erythematous, raised and expanding margin;
  • Histology:
    • Palisaded granulomatous dermatitis involving full thickness dermis and extending to the subcutaneous fat;
    • Palisades in a horizontal and parallel arrangement to the epidermis;
    • Marked central collagen degeneration without connective tissue mucin;
    • Fibrotic dermis in the periphery of the palisades (normal in GA);
    • Superficial and deep perivascular inflammation with numerous plasma cells.

Rheumatoid Nodule

  • Present in ~20% patients with rheumatoid arthritis;

  • Location: over the joint, classically elbows, other locations include knuckles, Achilles tendon;

  • Histology:

    • Within the dermis and subcutis, zones of eosinophilic collagen alteration and a mild infiltrate;

    • Palisaded granulomatous dermatitis with a large central homogenous eosinophilic fibrinoid necrosis;

    • The central area lacks connective tissue mucin.

Necrobiotic Xanthogranuloma

  • ~ 80% cases associated with IgG paraproteinemia;

  • Common systemic manifestations: hepatosplenomegaly, arthritis, arthralgias and neuropathy;

  • Location: mostly periobitally, also trunk and extremities;

  • Gross: indurated papules, nodules, or plaques;

  • Histology:

    • The lesion extends throughout the dermis, and sometimes into the subcutaneous fat;

    • Broad zones of collagen degeneration and cholesterol clefts surrounded by foamy macrophages with foreign body giant cells;

    • Prominent lymphocytes and plasma cells.

Palisaded Neutrophilic and Granulomatous Dermatitis

  • Associated with SLE, rheumatoid arthritis, Wegener's granulomatosis, and inflammatory bowel disease;

  • Location: symmetrically distributed on the extremities;

  • Gross: skin-colored, to erythematous papules with overlying crust, ulceration, or umbilicated surfaces;

  • Histopathologic examination demonstrates a spectrum of changes that reflect the evolution of the lesions

    • Early lesions: characterized by leukocytoclastic vasculitis with dense neutrophilic infiltrates and degenerated collagen;

    • Fully developed lesions: palisaded granulomas surrounding leukocytoclastic debris, fibrin, and altered collagen; the central area contains connective tissue mucin;

    • Late-stage lesions: characterized by palisaded granulomas with dermal fibrosis and scant neutrophilic debris.