Squamous cell carcinoma (SCC) is the most common malignant tumor at the nail unit. It mainly affects middle-aged men, with a peak incidence between 50 and 69 years of age. Diagnosis is often delayed because of the slow evolution of the lesion and multiple clinical features.

We sought to characterize the different clinical and histopathological patterns of SCC of the nail unit and evaluate their therapeutic outcome.

Records for 58 patients were retrieved from our department's dermatopathology database over a period of 15 years (1995-2011) and the patients recontacted.

Of the 58 patients, 51 were eligible for follow-up. There was a male predominance (72.5%). The fingers were most commonly affected (98%), the right index and long fingers being most commonly affected (20.8% each). The nail bed was mainly affected. The commonest clinical signs were, in decreasing order, subungual hyperkeratosis, onycholysis, oozing, and nail plate destruction. The majority of SCC of the nail unit was in situ (63%). The recurrence rate of all treatments taken together was 30.6%.

Retrospective study design is a limitation.

SCC of the nail unit mostly affects men aged 50 to 69 years. Most cases were the warty type, with oozing being an underrecognized clinical sign. Contrary to prior studies, most lesions were in situ, and bone involvement was uncommon. Conservative surgical resection should be the first-line treatment when the bone is not involved. Recurrence rate is high when a procedure other than Mohs micrographic surgery is performed.