Thymic Adenocarcinoma With Metastasis to the Left Orbit: A Case Report

We present the case of a 57-year-old female who initially presented with a chief complaint of left-sided orbital headaches and associated left eyelid swelling. Initial imaging work-up with CT head/orbit revealed soft tissue enhancement of the left orbital roof, concerning for neoplastic process (primary lymphoma versus extracranial primary tumor versus metastatic tumor). Further imaging studies with CT chest/abdomen/pelvis revealed an anterior mediastinal mass, concerning for possible thymoma versus lymphoma. The patient underwent further consultation with the Hematology/Oncology and Ophthalmology Departments, which recommended definitive biopsies from both sites, which showed matching histologic findings of moderately differentiated enteric-type adenocarcinoma with positive staining for CDX2, an intestinal marker. Thymic carcinomas are rare cancers that account for approximately 0.06% of all malignancies and require a high degree of clinical suspicion. Extrathoracic metastases from thymic carcinomas, especially to the orbit, is a rare occurrence and the exact incidence of this phenomenon is unknown. This case represents the diagnostic challenges associated with a rare cancer type and underscores the importance of a multidisciplinary approach to patient care.