Pseudoepitheliomatous hyperplasia formation after skin injury.

Pseudoepitheliomatous hyperplasia (PEH) is characteristic of reactive epithelial downward proliferation into the dermis. To explore the mechanism of PEH formation, we investigated the cause, clinical characteristics, histopathologic change, and clinical treatment of PEH, the expression characteristics of stem cell factor (SCF), and its receptor c-Kit in PEH and normal skin of PEH edge (PEH-N). The clinical data of 11 patients with PEH were reviewed, and biopsy examination and bacterial cultures were performed. The histological features of PEH and expression levels of SCF, c-Kit were examined with the pathological method and immunohistochemical methods. The results showed that in each case, histological examination revealed epidermal hyperplasia with irregular cords of epithelial cells extending into the dermis. The bacteria could be cultured and isolated from all PEH biopsies. These bacteria were resistant to several antibiotics, except vancomycin. Radical excision and daily dressing with vancomycin could cure PEH. SCF protein was expressed at stronger levels in sweat gland epithelial cells and interstitial cells of the PEH group vs. the PEH-N group. c-Kit was more strongly expressed by interstitial cells in PEH than in PEH-N. It was concluded that the improper management of cutaneous wounds might cause PEH formation, which can be cured by surgical excision and administration of effective antibiotics. SCF and c-Kit might be involved in the epidermal hyperplasia observed in PEH.