Orbital Manifestations as the First Clue: A Comprehensive Case Series Highlighting the Role of PET/CT in Diverse Orbital Pathologies

Orbital diseases frequently manifest with non-specific symptoms like proptosis, diplopia, pain, or visual disturbances, but still may be the first sign of various underlying pathologies, ranging from benign inflammation to aggressive malignancies. Early diagnosis is crucial but challenging with conventional imaging. We present a case series of fourteen patients with primary orbital or ocular complaints who underwent whole-body positron emission tomography/ computed tomography (PET/CT). Diagnoses included orbital lymphoma, leukaemia, rhabdomyosarcoma, Ewing’s sarcoma, multiple myeloma, metastatic carcinomas (breast, lung, thyroid), sebaceous and squamous cell carcinoma, hidradenocarcinoma, Erdheim-Chester disease, IgG4-related disease, and optic nerve sheath meningioma. 18 F-FDG PET/CT enabled metabolic characterisation of the orbital lesions and revealed occult systemic disease, significantly influenced staging, guided biopsy and treatment decisions. Advanced tracers such as 68 Ga-FAPI and 68 GaDOTATATE improved specificity in selected conditions. Overall, PET/CT serves as a comprehensive “one-stop” modality, integrating anatomical and metabolic data to optimise the diagnosis and management of orbital diseases.