Sinonasal Malignant Melanoma and the Orbit

Introduction: Primary sinonasal melanoma (PSM) is thought to arise from mucosal melanocytes, which in turn are of neural crest origin. Mucosal melanoma is rare, comprising less than 1% of all melanomas; and Ff all nasal cavity and sinus malignancies, melanoma comprises 6%. Mutations in NRAS, KIT, and BRAF are commonly seen in this disease. Survival is poor and case series in the literature report 5-year survival between 14 and 33%. We review here 19 cases of PSM and examine whether direct extension to the orbit is a poor prognostic factor.

Methods: In this retrospective case series, we examined 19 patients (13 women and 6 men) with nasal cavity or sinus melanoma. We excluded patients with oral or pharyngeal melanoma. We review demographics, clinical features, and Kaplan–Meier survival data comparing patients with direct orbit extension versus those without evidence of orbital disease.

Results: In this series, PSM arose from the paranasal sinuses in 8/19 (42%) and in the nasal cavity in 11/19 (58%). Median age at diagnosis was 71 years. All patients presented with nasal congestion or epistaxis or both. The most common orbital signs were diplopia, proptosis, tearing, and pain. Local extension of tumor into the orbit was noted in nine patients. Sinus melanoma (6/8, 75%) invaded the orbit more frequently than nasal cavity melanoma (3/11, 27%). Seven patients were lost to follow-up. For patients with complete follow-up, the median survival for patients without orbital extension (n = 7) was 48 months, and for those with orbit extension (n = 5), it was 12 months. This difference trended toward statistical significance (p = 0.06, logrank; p = 0.03, Gehan–Breslow–Wilcoxon). Overall 5-year survival in this series was 27%. All patients with complete follow-up died of disseminated disease.

Discussion: The overall survival rates reported in this study agree well with those reported in other series. Likewise, the lower median survival seen in patients with orbit involvement agrees well with American Joint Committee on Cancer staging guidelines, which state that invasion of sinonasal malignant melanoma into the orbit or skull base is classified as “very advanced” disease.

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