PurposeTo describe a case of idiopathic multicentric Castleman's disease (iMCD) with initial ocular involvement, presenting with chorioretinal undulation.MethodsObservational case report of iMCD patient with ocular manifestation on fundus photography, auto-fluorescein and swept-source optical coherence tomography (SS-OCT), initially and after treatment.ResultsA 75-year-old patient with painless vision loss for 2 years right eye (RE) and 3-month left eye (LE). Fundus examination revealed several yellow-white lesions along with the inferior arcade, with extensive pigment disturbance of the right eye and exudative retinal detachment of the left eye. SS-OCT showed choroid and retinal pigment epithelium (RPE) undulations, choroid thickening and hyperreflective dots at the choroidal level. Interleukin-6 (IL-6) in the anterior chamber was very high (1595 pg/ml RE and 749.3 pg/ml LE). After cervical lymph node biopsy, the patient was finally diagnosed with iMCD. Siltuximab, an interleukin-6 inhibitor, was administered. After two cycles of therapy, the patient's ocular manifestations improved significantly, the choroid and RPE undulation and the ERD resolved without local treatment.ConclusionChorioretinal undulation and elevated IL-6 in intraocular fluid could be ocular manifestations of MCD.