Subungual squamous cell carcinoma and exostosis in third toe - case report and literature review

Background Squamous cell carcinoma (SCC) in the ungual apparatus is a rare neoplasia. Although it is the most prevalent malignant tumour in this region, its diagnosis is often delayed because it is likened to benign or infectious processes. Objectives Present a case of SCC with subungual location in a toe, and carry out a review of the literature in relation to the most important aspects of subungual SCC in toes. Methods We describe the case of a white woman aged 72, with SCC located in the pulp and in the distal area of the nail bed of the third toe, associated with subungual exostosis. The literature on SCC in the subungual area of toes, in all its forms under clinical or histopathological presentation, is reviewed by means of a search involving Medline, PubMed, and Google Academic, from January 1994 to December 2011. Results Only 36 cases of subungual SCC in toes were reported in the 18 years that were reviewed. The average age of cases reviewed was 58.92, and the male-to-female ratio was 2 : 1. The most affected toe is the hallux, in 69.4% of cases. In 50% of cases, aetiology is unknown or indeterminate; in 22.3% of cases, aetiology is metastatic; and in 19.5% of cases, it is associated with human papillomavirus (HPV). In 58.2% of cases, partial or total resection of the distal phalanx was carried out, of the entire toe, or of the osseous ray of the foot. Conclusions Chronic tissue irritation caused by microtrauma associated with subungual exostosis is the most probable aetiology of the case presented.