Relapsed Retinoblastoma with Late Skeletal Metastasis in a Pediatric Patient.

Retinoblastoma is the most common pediatric intraocular malignancy and rarely presents with distant metastases. We present the case of a 6-y-old boy with unilateral retinoblastoma who developed extensive skeletal and bone marrow metastases 3.5 y after initial successful treatment. Imaging demonstrated multifocal involvement of the skull, long bones, and pelvic bones. Bone marrow biopsy confirmed metastatic round blue cell tumor compatible with retinoblastoma, with no cerebrospinal fluid involvement. This case highlights the risk of late osseous metastasis in relapsed retinoblastoma and emphasizes the role of multimodality imaging and pathologic confirmation for accurate diagnosis and management.