Pseudoepitheliomatous hyperplasia (PEH) is a benign condition characterized by an overgrowth of skin cells in the epidermis, the outermost layer, and associated structures like hair follicles and sweat glands. This condition is not a form of cancer but a reactive proliferation of cells. Despite its benign nature, PEH can closely resemble squamous cell carcinoma, often leading to initial concerns about malignancy.
Underlying Causes and Triggers
PEH is a reactive process triggered by external stimuli or underlying disease. It often arises from prolonged inflammation or chronic infection. Causes include chronic wounds, ulcers, trauma, deep fungal infections, mycobacterial infections, tuberculosis, and syphilis. It can also be associated with skin conditions or underlying tumors, such as granular cell tumors and melanocytic lesions. Cases are also reported following tattooing and Mohs micrographic surgery.
Clinical Presentation and Symptoms
PEH lacks distinctive clinical features. It appears as a well-demarcated plaque or nodule, with variable scaling and crusting. Ulceration may be present.
Lesions range from less than 1 cm to several centimeters, depending on the underlying cause. The lesion’s color may be similar to surrounding mucosa or pigmented. Common locations include skin, oral mucosa (gingiva, palate, tongue), and sites of chronic irritation or injury.
Diagnosis and Differentiating from Cancer
Skin biopsy with histopathological interpretation is the gold standard for diagnosis. PEH shows irregular, jagged, often pointed epidermal cell masses and strands invading the dermis. It exhibits extensive acanthosis (epidermal thickening) with irregular downward projections. Keratin pearl formation (concentric layers of keratinocytes with central keratinization) may be present.
Histologically, PEH cells are well-differentiated and lack nuclear atypia, abnormal mitoses, or dyskeratosis, characteristic of SCC. Inflammatory cell infiltrate (e.g., leukocytes) is common in PEH, usually absent in SCC.
SCC shows significant squamous cell atypia, abnormal keratinization, and invasive features like vascular, lymphatic, or perineural invasion, which are absent in PEH. Careful evaluation of multiple sections, especially including the lesion’s base, and strong clinicopathological correlation are required to differentiate PEH from SCC.
Treatment and Management
The primary approach is to address the underlying cause. For infections, antibiotics or antifungals are appropriate. For chronic wounds, proper wound care is necessary.
Surgical excision is a common and recommended treatment option. Excision confirms diagnosis and serves as a cure. Grafts or flaps may be required for reconstruction if the tissue defect is severe. Prognosis is good once the underlying trigger is managed.