Metastatic Merkel cell carcinoma presenting as an orbital mass

A 67-year-old female presented with 2 weeks of right eye pain, redness, and diplopia. An orbital mass was found on magnetic resonance imaging (MRI), and biopsy revealed Merkel cell carcinoma (MCC). She had no primary head or neck lesion and no previous history of MCC. Positron emission tomography (PET) scan showed hypermetabolic subcutaneous lesions of the lower extremity andmultiple osseous lesions of the axial and appendicular skeleton. She received palliative external radiation of 20 Gy in 5 fractions to the orbit. After discussing immunotherapy, she opted for comfort care and expired 1 month later. To the best of our knowledge, this is only the third case of MCC with distant metastasis to the orbit and the first case in which the patient had no previous diagnosis of MCC and no known primary tumor.