Exploring Potential Orbital Metastatic Pathways in Sinonasal Mucosal Melanoma: A Case Report.

The following case potentially provides insight into the mechanisms of lymphogenic metastasis in sinonasal cancer. A 63-year-old patient who presented with progressive diplopia and left-sided periocular pain was diagnosed with a cT4bN0M0 mucosal melanoma of the ethmoid sinus. She underwent a combined endonasal and transcranial tumor resection, and an orbital exenteration. Upon histopathological examination, besides the primary tumor, two separate localizations of melanoma surrounded by lymphoid tissues and lymph follicles were identified. The tumor was upstaged to pT4bN1, and the patient received a combination of adjuvant immunotherapy and radiotherapy. At present, the patient displays no evidence of disease. The presence of orbital lymph nodes has previously never been confirmed. These findings indicate the potential involvement of lymphatic drainage through the retrobulbar fat in the regional spread of sinonasal tumors closely associated with the orbit.