Squamous Cell Carcinoma of the Nail Unit: A Clinical Histopathologic Study and a Proposal for Classification.

BACKGROUND: There is no consensus on the classification, grading, and the treatment of nail squamous cell carcinoma (NSCC). OBJECTIVE: The aim of the study was to propose a possible classification of NSCC. MATERIALS AND METHODS: Nail squamous cell carcinoma referred from January 2006 till December 2014 was included. On the basis of the clinical presentation, patients with NSCC were divided in 2 groups. Group A tumors presented as nodular or ulcerated masses of the nail bed, whereas Group B tumors presented as hyperkeratotic bands. In these 2 groups, differences in proportions (sex, histopathologic grading, and treatment performed) were evaluated with the chi-square test. RESULTS: Forty-one NSCCs were included. The groups of NSCC differed regarding: (1) the age of the patients, (2) histopathology, and (3) surgical approach. CONCLUSION: Nail squamous cell carcinomas may originate from 2 different epithelia, presenting a diverse clinical behavior. The correct identification and diagnosis of each subgroup of NSCC could be helpful in standardizing management of this tumor. Future studies considering human papillomavirus subtyping and including a major number of tumors should be performed to confirm or reject the authors' hypothesis. LIMITATIONS: This is a retrospective study, presenting the data and the experience of a single institute