Cutaneous pseudoepitheliomatous hyperplasia (PEH) is a benign reactive phenomenon characterized by a thickened epidermis that appears clinically as a hyperkeratotic or verrucous lesion. Clinically, patients present with verrucous papules on the skin or mucosa in association with trauma (eg, burns, skin tears, foreign body reactions in association with tattoos, permanent makeup, arthropod bites, Mohs surgery), infection (ie, bacterial, mycobacterial, parasitic, fungal, and less commonly viral), prolonged inflammation (eg, lymphedema, elephantiasis nostras verrucosa, chronic wounds, inflammatory dermatoses such as prurigo nodularis, lichen simplex chronicus, lichen planus, hypertrophic lupus erythematosus, pemphigus vegetans, pyostomatitis vegetans, lichen sclerosus, halogenoderma, pyoderma gangrenosum), or neoplasms (eg, melanoma, basal cell carcinoma, Spitz nevus, atypical fibroxanthoma, T-cell lymphoma, granular cell tumor, salivary gland pleomorphic adenoma, metastatic breast carcinoma).

PEH is a poorly understood condition, but it is thought to represent hyperplasia of the epidermis and adnexal epithelium as a physiologic response to skin damage. PEH poses a diagnostic dilemma as it clinically and histologically mimics squamous cell carcinoma.