Choroidal Osteoma with Focal Choroidal Excavation Masquerading as Active Vogt-Koyanagi-Harada: A Case Report

Introduction: Choroidal osteoma is a rare, benign ossifying tumor of the choroid that can present with clinical features overlapping those of inflammatory choroidal lesions. In patients with a history of Vogt-Koyanagi-Harada (VKH) disease, distinguishing between inflammatory relapse and non-inflammatory choroidal pathology can be particularly challenging. This case report highlights the diagnostic pitfalls associated with choroidal osteoma in the setting of prior VKH and underscores the importance of comprehensive multimodal imaging to ensure accurate diagnosis and appropriate management. Case Presentation: A 39-year-old female with a 14-year history of VKH disease, who had been stable off immunosuppressive therapy since 2016, presented in early 2024 with a 7-week history of cloudy vision in the right eye. She was initially diagnosed with a recurrent posterior VKH relapse and treated with high-dose intravenous corticosteroids followed by an oral taper, resulting in symptomatic improvement. However, further multimodal imaging - including wide-field fundus photography, optical coherence tomography (OCT), fundus autofluorescence, OCT angiography, fluorescein angiography, enhanced depth imaging OCT (EDI-OCT), and B-scan ultrasonography - revealed a yellow-orange, minimally elevated subretinal lesion associated with focal choroidal excavation. These findings were consistent with choroidal osteoma and confirmed by EDI-OCT and B-scan ultrasonography. Conclusion: This case illustrates a rare instance of choroidal osteoma masquerading as a posterior relapse of VKH disease. It emphasizes the critical importance of differentiating inflammatory from non-inflammatory choroidal lesions in patients with a history of uveitis. Careful interpretation of multimodal imaging is essential to avoid misdiagnosis, prevent unnecessary immunosuppressive treatment, and reduce associated risks, ultimately leading to improved patient outcomes.