EPIDEMIOLOGY: Up to 6% of squamous cell carcinomas (SCC) and 3% of basal cell carcinomas (BCC).
ETIOLOGY: As with BCC and SCC, primarily accumulated ultraviolet exposure.
PATHOGENESIS: Upregulation of TGF-beta, with resulting downregulation of epithelial-cadherin and overexpression of (neural)-cadherin. Other cell adhesion molecules including caveolin-1 (cav-1) and bystin may be involved.
CLINICAL: Associated with other signs of aggressive cancers such as large size (>2 cm), Breslow level (>4 mm) and more aggressive histologic subtypes. Most common anatomic locations include the lip, ear, forehead, scalp, temple and dorsal hand. Cancers with PNI are more likely to present to the Mohs surgeon as recurrences either from traditional surgical excision or from previous Mohs surgeries. Neurologic signs or symptoms may be present.
HISTOLOGY: In the immediate presence of a non-neural dermal malignancy, PNI may be diagnosed by the observation of malignant cells in the perineural space of peripheral nerves.
KeywordsSquamous Cell Carcinoma Skin Cancer Basal Cell Carcinoma Local Control Rate Cutaneous Squamous Cell Carcinoma