Pseudoepitheliomatous Hyperplasia
The hyperplasia that occurs during wound healing in psoriasis patients is called pseudoepitheliomatous hyperplasia (PEH).
What is Pseudoepitheliomatous Hyperplasia?
Pseudoepitheliomatous hyperplasia is characterized by reactive epithelial downward proliferation into the dermis, manifesting as irregular cords of epithelial cells extending from the epidermis into deeper tissue layers 1. This represents an exaggerated wound healing response rather than a malignant process, despite its sometimes alarming histological appearance.
Key Clinical Features
The condition develops specifically in the context of:
- Improper wound management following cutaneous injury in psoriatic skin
- Bacterial colonization - cultures consistently grow bacteria from PEH lesions, often resistant to multiple antibiotics except vancomycin 1
- Epidermal hyperplasia with downward extension that can mimic squamous cell carcinoma histologically
Pathophysiological Mechanism
The formation of PEH involves dysregulated stem cell signaling:
- Stem cell factor (SCF) shows stronger expression in sweat gland epithelial cells and interstitial cells within PEH tissue compared to normal adjacent skin
- c-Kit receptor demonstrates increased expression by interstitial cells in affected areas
- This SCF/c-Kit pathway activation drives the abnormal epidermal proliferation characteristic of PEH 1
Clinical Management
Definitive treatment requires radical surgical excision combined with daily vancomycin dressings to address both the hyperplastic tissue and underlying bacterial infection 1. This dual approach targets both the structural abnormality and the infectious trigger that perpetuates the condition.
Important Distinction
This phenomenon differs from the baseline epidermal hyperproliferation seen in psoriatic plaques themselves, which involves keratinocyte hyperproliferation driven by inflammatory cytokines and immune dysregulation 2, 3. PEH represents a specific complication of wound healing rather than the primary disease process.