Functional Surgery for Malignant Subungual Tumors: A Case Series and Literature Review

Amputation is the conventional treatment for malignant subungual tumors (MSUTs), namely, subungual squamous cell carcinoma (SUSCC) and subungual melanoma (SUM). Functional surgery consisting of wide local excision (WLE) of the nail unit can preserve function without modifying prognosis in such cases. We present a series of MSUTs treated with WLE of the nail unit, describe the technique, and review its indications.

Retrospective observational study of MSUTs treated with WLE of the nail unit between 2008 and 2017. The technique consisted of en bloc supraperiosteal excision of the nail unit with a margin of 5mm followed by repair with a full-thickness graft.

Eleven MSUTs were treated in the study period: 7 SUMs (4 in situ; mean thickness, 1.17mm; range, 0-4mm) and 4 SUSCCs (mean thickness, 3.4mm; range, 1.6-6mm). WLE of the nail unit was performed in 9 patients and amputation in 2 patients with invasive SUM. Mean follow-up was 39 months (range, 12-96 months) and no local or regional recurrences were detected. One of the 2 patients who underwent amputation developed metastasis to the brain and died. In our review of the literature, we identified 5 series of patients with SUSCC treated with WLE of the nail unit (105 patients) and 14 series of patients with SUM (243 patients). Based on an analysis of these cases and ours, it would appear that WLE of the nail unit is associated with a very low rate of local recurrence (<7%) and offers better functional and cosmetic outcomes than amputation.

WLE of the nail unit is the treatment of choice for SUSCC without bone involvement and for thin noninvasive SUM (Breslow depth <1mm). It is also feasible in intermediate-thickness SUMs when detailed histologic examination of the margins confirms complete resection. Amputation, by contrast, is the treatment of choice for SUSCCs with bone involvement, very thick SUMs (>4mm), and recurrent tumors.