Puzzling Late Relapse of Thyroid Eye Disease: A Case Series.

Thyroid eye disease (TED) is a self-limiting autoimmune inflammatory condition that lasts an average of 18 to 36 months. Late recurrence of TED, defined as new onset of active orbitopathy after 5 years of quiescence, is rarely reported. We retrospectively audited all patients with TED relapse between 2016 and 2024. Case 1, a 69-year-old female individual, presented with recurrent TED 40 years after the initial episode. Case 2, an 86-year-old female individual, reactivated initially 20 years, and then again 34 years, after the primary TED presentation. Case 3, a 52-year-old male individual, relapsed 9 years after the initial episode. In all cases, TED relapse was confirmed with clinical examination, elevated thyrotropin receptor antibodies (TRAb) and characteristic radiological features. All 3 cases were managed with various combinations of rituximab, intravenous methylprednisolone, oral mycophenolate mofetil, ciclosporin, oral methotrexate, orbital radiotherapy, and orbital decompression surgery. All achieved quiescent disease. This case series highlights the potential for late-onset relapse, sometimes several decades after the initial presentation and illustrates the potential severity of TED and need for multimodal treatment. Clinicians should be aware of the possibility of TED relapse and warn patients at discharge.