Experience‐based recommendations for the diagnosis and management of early‐stage nail unit melanoma

BACKGROUND: Nail unit melanoma (NUM) is a distinct form of melanoma that most often arises from the nail matrix. No recommendations as to the management of nail melanoma, particularly of early-stage melanoma (in situ, stage IA, IB), exist. OBJECTIVES: To provide practical, experience-based recommendations for the diagnosis, differential diagnosis and management of early-stage NUM, developed by an international expert panel. METHODS: Based on clinical and histopathological experience and an extensive literature search, the authors present recommendations for the management of patients with lesions suspicious for NUM. RESULTS: Clinically, most cases present as a longitudinal pigmented band in an adult nail. It represents 1.5-2.5% of all melanomas in Caucasians but up to 50% in Black patients. Considering that the nail unit surface area accounts for less than 1% of the total body surface, the nail matrix can be regarded as a hotspot for melanoma development. Early diagnosis is critical, as treatment at the in situ or minimally invasive stage is associated with high cure rates. While dermoscopy is a useful diagnostic aid, nail matrix biopsy with histopathology remains the gold standard. Laboratory tests and standard imaging studies are not diagnostic; however, they may assist in surgical planning for advanced cases. Complete surgical excision is the treatment of choice. Wide local excision is recommended for early-stage disease, with specific margins (6 mm for standard lesions; 10 mm in the presence of the Hutchinson sign). Amputation is generally reserved for thicker tumours (>1 mm). A 10-year follow-up period is recommended to monitor for potential recurrence. CONCLUSIONS: Early diagnosis and treatment of nail unit melanoma at the in situ or minimally invasive stage (IA/IB) are associated with high cure rates. In contrast, advanced disease with deep invasion or metastasis carries a poor prognosis-therefore, timely recognition and intervention are essential to optimize outcomes.