A NEW single-institution study from Japan sheds light on the clinical behaviour and prognostic factors of nasal cavity and paranasal sinus mucosal melanoma (NPMM) in the era of immune checkpoint inhibitors (ICIs), highlighting important differences between tumour subtypes and identifying a potentially useful biomarker.
Mucosal melanoma arising in the nasal cavity and paranasal sinuses is rare and aggressive, with historically poor outcomes. While ICIs have become the cornerstone of systemic treatment, real-world data on how these tumours behave in the immunotherapy era remain limited. To address this gap, researchers retrospectively analysed 23 patients treated between 2015 and 2023, including 15 with nasal cavity mucosal melanoma (NMM) and eight with paranasal sinus mucosal melanoma (PMM).
Paranasal Melanoma Linked to Poorer Survival Outcomes
Almost all patients (95.7%) received ICI therapy, reflecting current clinical practice. The study found marked differences between the two subtypes. Patients with PMM presented with significantly larger tumours and more frequent bone invasion compared with those with NMM. These features translated into poorer outcomes, with PMM patients experiencing shorter progression-free survival.
The analysis also identified notable differences in blood parameters. PMM patients had higher neutrophil counts and lower lymphocyte and platelet counts. While individual neutrophil or lymphocyte levels were not independently associated with survival, the neutrophil–lymphocyte ratio (NLR) emerged as a significant prognostic marker. An NLR of ≥4 was associated with worse outcomes, suggesting that this simple, routinely available metric could help stratify risk in clinical practice.
Additional factors linked to poorer prognosis included tumour size ≥45.5 mm, lower platelet counts (≤247.5 × 10³/μL), and origin in the paranasal sinuses. Together, these findings reinforce the more aggressive nature of PMM compared with NMM.
New Insights into Prognostic Factors for Rare Mucosal Melanomas
Although limited by its small sample size and retrospective design, the study provides valuable real-world insight into NPMM in the ICI era. The authors suggest that NLR, in particular, may serve as a practical and accessible biomarker to guide prognosis and potentially inform treatment strategies.
Further larger-scale studies are needed to validate these findings and refine risk stratification for this challenging malignancy.
Reference
Waki Y et al. Clinical features of nasal and paranasal mucosal melanomas in the era of immune checkpoint inhibitors: insights from a single-institution analysis. J Dermatol. 2026; DOI:10.1111/1346-8138.70258.
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