Palisaded neutrophilic granulomatous dermatitis
Although the exact etiology is unknown, PNGD is likely a reactive process with histological patterns ranging from early neutrophilic inflammation and leukocytoclastic vasculitis to collagen degeneration, granuloma formulation, and associated fibrosis.
PNGD is seen in patients of all ages, though reports of affected children are rare. Women are affected more than men in a 3:1 ratio, which likely reflects the demographics of common underlying autoimmune diseases. Systemic lupus erythematosus and rheumatoid arthritis are the most common associations, although inflammatory bowel disease and systemic vasculitides have also been reported. PNGD has also been rarely reported in association with myelodysplastic syndrome and other lymphoproliferative conditions. It may precede the malignancy diagnosis by up to 5 years, or it may be present at the time of diagnosis.
PNGD presents as symmetrically distributed, skin-colored to erythematous, umbilicated or crusted papules, typically on the elbows and extensor surfaces.
Related topic: paraneoplastic granulomatous eruption
L30.9 – Dermatitis, unspecified
402432002 – Rheumatoid neutrophilic dermatitis
Differential Diagnosis & Pitfalls
- Interstitial granulomatous dermatitis – Classically presents as linear subcutaneous cords or bands on the proximal trunk but may have substantial morphological overlap with PNGD. Proximal limbs and trunk tend to be involved. The absence of vasculitis on histology distinguishes it from PNGD.
- Interstitial granulomatous drug reaction – Erythematous to violaceous annular or nonannular plaques on the trunk, inner upper arms, proximal thighs, and intertriginous skin; typically preceded by a new drug exposure.
- Granuloma annulare – Nonscaly erythematous papules or plaques on the trunk or extremities. Histology demonstrates a lymphocytic infiltrate with mucin deposition rather than neutrophilic infiltrate.
- Bowel-associated dermatosis arthritis syndrome
- Erythema elevatum diutinum