Squamous cell carcinoma presenting as an orbital cyst with radiologic evidence of perineural invasion

PURPOSE. To report clinical and radiologic findings of cystic squamous cell carcinoma (SCC) of the orbit with evidence of perineural involvement. METHODS. Analysis of clinical findings and radiology with a literature review. RESULTS. A 66-year-old man with SCC of the forehead 8 years prior presented with paraesthesias, diplopia, and proptosis. Magnetic resonance imaging showed a well-defined, cystic mass of the orbit with a single, linear structure running through its center. Lateral orbitotomy revealed a cyst adherent to adjacent periorbita containing viscous, clear, yellow substance and a nerve coursing through the center. Histopathology confirmed poorly differentiated spindle cell carcinoma with positive staining for cytokeratin markers, consistent with SCC. CONCLUSIONS. Orbital cysts associated with altered sensation are suggestive of SCC with perineural spread, requiring prompt investigation and treatment to minimize morbidity and mortality. The involved nerve may be seen as a single, linear structure within the mass on imaging.