Sinonasal Mucosal Epithelioid Melanoma with Rapid Skull-Base and Orbital Progression

<b>Background</b>: Sinonasal mucosal melanoma is a rare and aggressive malignancy arising from the nasal cavity and paranasal sinuses, characterized by high local recurrence rates and poor survival. Skull-base and orbital progression can occur rapidly, particularly when preoperative imaging underestimates local extension. This paper reports a case of sinonasal mucosal epithelioid melanoma with fulminant postoperative skull-base breach and orbital invasion, highlighting its clinical course, management challenges, and histopathological features. <b>Methods</b>: A 60-year-old woman with progressive unilateral nasal obstruction, recurrent epistaxis, and headache underwent clinical evaluation, contrast-enhanced head MRI, CT, and PET-CT staging. Preoperative imaging demonstrated no intracranial or orbital invasion. Biopsy confirmed mucosal epithelioid melanoma with high proliferative activity (Ki-67 ~80-85%). The patient underwent extensive image-guided endoscopic resection with intraoperative cerebrospinal fluid leak repair. <b>Results</b>: Definitive histopathology confirmed pigmented epithelioid melanoma with extensive necrosis, bone invasion, and non-assessable resection margins due to specimen fragmentation (pT4a, Rx). Within two weeks postoperatively, CT and MRI demonstrated extensive local recurrence with cribriform plate destruction, anterior skull-base dural infiltration, and rapid orbital progression with optic nerve compression and loss of vision. Despite hemorrhage control and hypofractionated palliative radiotherapy (VMAT, 33 Gy in 11 fractions), the patient experienced progressive neurological decline, refractory pain, and recurrent tumour bleeding, and died approximately 4.5 months after initial presentation. <b>Conclusions</b>: In patients with sinonasal mucosal epithelioid melanoma, fulminant local progression with skull-base and orbital involvement may occur despite apparently limited preoperative imaging. When rapid vision loss, dural infiltration, and refractory nasal bleeding develop, structured palliation, hemorrhage control, and aggressive multimodal analgesia should be prioritized early alongside ongoing multidisciplinary decision-making.