Pyoderma gangrenosum (PG) begins as a painful pustule or nodule that breaks down into an ulcer with a characteristic undermined violaceous border. The pathological mechanism underlying PG is:

• A IgE-mediated mast cell degranulation
• B T-cell mediated granuloma formation
• C Neutrophilic dysregulation with pathergy ✓
• D Fibrinogen deposition and vasospasm

Explanation

Pyoderma gangrenosum is a neutrophilic dermatosis driven by neutrophilic dysregulation—excessive recruitment and activation of neutrophils in the dermis. A critical clinical feature is pathergy: new lesions triggered by minor trauma or surgical debridement. This paradox (surgery worsening the wound) is diagnostically important; biopsy or debridement of PG can worsen the ulcer. Associated systemic diseases include IBD (~50%), arthritis, haematological malignancies (IgA paraprotein) and solid tumours.

Reference: Neena Khanna Illustrated Synopsis of Dermatology & STD, 6th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.