Nail unit squamous cell carcinoma: A multicenter, retrospective study of the clinical and morphologic characteristics of 261 patients.

BACKGROUND

Nail squamous cell carcinoma (NSCC) is the most common nail malignancy, yet it is under-recognized because of its variable presentation.

OBJECTIVE

Characterize demographic and clinical characteristics associated with in situ (NSCCis) and invasive (iNSCC) NSCC and evaluate treatment outcomes in a multinational cohort.

METHODS

Two-hundred-sixty-nine NSCCs (261 patients) were retrospectively reviewed. NSCCis and iNSCC characteristics were compared using t-tests/chi-square and multinomial logistic regression.

RESULTS

NSCC mainly affected the right index and middle fingers and bilateral thumbs (62%), predominantly in men (72.4%) in their sixth decade. Koilocytosis, used to determine human papilloma virus (HPV) status, was detected in 32.2% of tumors (15 polymerase chain reaction-confirmed), and this was more common in NSCCis (P = .015). Subungual ooze independently predicted iNSCC (odds ratio = 3.98; 95% CI = 1.19-13.2; P = .025), while pain (P = .022) and nail plate loss (P = .004) were associated with iNSCC on univariate analysis. Mohs micrographic surgery was the most common treatment (39.5%). Overall recurrence was 9.7%, with no difference among treatments (P > .05).

LIMITATIONS: Retrospective design and histopathology-based HPV status.

CONCLUSIONS

NSCC presents as a periungual papule/plaque with horizontal growth and a warty appearance, or as an oozing subungual ulcerating tumor, dermally invasive. Periungual NSCC is associated with HPV, often sexually transmitted. HPV-related cases are typically NSCCis. Digit-sparing surgery is first-line treatment, with comparable efficacy across modalities.