Squamous cell carcinoma of the lung presenting as paraneoplastic antibody positive orbital myositis with review of literature.

Paraneoplastic syndromes with ophthalmic involvement are rare but can signal an underlying malignancy. We describe an 82-year-old African American male with worsening vision and bilateral recurrent compressive optic neuropathies after undergoing successful orbital decompressions for presumed thyroid eye disease. Imaging demonstrated enlargement of all rectus muscles with a tight apex and a left hilar mass. Additional laboratory testing was positive for P/Q Type Voltage Gated Calcium Channel Binding Antibody (VGCC). A biopsy of the lateral rectus muscle confirmed orbital myositis and a biopsy of the apical mass revealed squamous cell carcinoma of the lung. Pembrolizumab was started, and the vision improved to count fingers with resolution of the orbital compartment syndrome and improvement in the orbital inflammation. To our knowledge, this is the first report highlighting the association of a positive paraneoplastic antibody in a case of orbital myositis.