Immunohistochemical findings and differential diagnosis of papillary-type cutaneous verrucous carcinoma of the neck: A case report.

Verrucous carcinoma (VC) is a rare subtype of squamous cell carcinoma, with the majority of cases occurring in the oral cavity and genital area. The present study describes a rare case of cutaneous VC of the neck manifesting as a semi-pedunculated multinodular protrusion. Histological analysis revealed thickening of the epidermis and papillary growth. Although cellular atypia was generally mild, a large number of mitoses were observed, of which a small number were abnormal. Additionally, bulbous subepidermal invasion was observed. The lesion was differentiated from papillary squamous cell carcinoma, another rare subtype of squamous cell carcinoma, based on the presence of epidermal verrucous growth and the lack of remarkable nuclear atypia. Benign disorders, including seborrheic keratosis, fibroepithelial polyp, verruca vulgaris and pseudocarcinomatous hyperplasia, were also differentiated from the lesion. Immunohistochemical analysis of cytokeratin (CK)10 expression revealed attenuated staining of the lesion, therefore, anti-CK10 immunohistochemistry may be valuable in the diagnosis of VC.