Melanoma of the nail apparatus: a systematic review and meta-analysis of current challenges and prognosis

Nail apparatus melanoma (NAM) is a rare dermatologic malignancy. Its prognosis is poor because it is often diagnosed late. However, progression and survival of NAM patients have only been studied among small populations. Early biopsy could help to identify suspicious lesions at a less invasive stage. While surgery is generally seen as the treatment of choice, the extent of excision margins and the use of sentinel biopsy remain debated. This systematic review aims to summarize the treatment procedures and observed prognosis in the literature during the last two decades and present pooled survival and progression rates of NAM by using meta-analysis. A systematic review on studies assessing pathology, treatment and prognosis of NAM was carried out up to end of 2018. After evaluation of eligible studies, the main emerging topics were outlined and pooled survival outcomes estimated. A total of 30 articles out of 624 identified records were included for systematic review. Finally, meta-analysis of pooled mortality rates including 18 studies was 4.6 x 100 patient-years (95% CI: 2.7, 6.8) equivalent to 5-year cumulative survival of 77.0%. Additionally, the pooled progression rate based on 17 studies was 6.3 x 100 patient-years (95% CI: 4.1, 8.9) with estimated 5-year cumulative progression-free survival of 68.5%. While the optimal extent of surgical treatment remains debated, prompt biopsy could help to identify early lesions. This is the first study to present pooled survival and progression rates by meta-analysis.