Vulvar Melanoma with Isolated Metastasis to the Extraocular Muscles: Case Report and Brief Literature Review

Background/Aim: Orbital metastasis of systemic cancer is exceedingly rare. This is a case report of a patient treated for locally recurrent vulvar melanoma who later presented with unilateral proptosis and was found to have an isolated biopsy-proven extraocular muscle metastasis. Patients and Methods: A 94-year-old female with locally recurrent vulvar melanoma presented with eye discomfort and blurry vision. Patient underwent histopathological, genetic, and imaging studies. Results: All prior work-up, including brain MRI and PET/CT, was negative for disease elsewhere from local recurrence. Orbital MRI demonstrated a mass involving the extraocular muscle, and immunohistochemistry staining of biopsy was consistent with metastasis. The patient underwent radiation therapy and tolerated treatment well. Conclusion: This is the first reported case of vulvar melanoma with extraocular muscle metastasis. The absence of findings on imaging as part of the staging work-up underscores the importance of considering extraocular muscle (EOM) metastasis as a differential for patients with vulvar melanoma who present with proptosis.