Clinical Characteristics and Image Manifestations of a Rare Retinoblastoma with a Bone Metastasis

Purpose: Retinoblastoma (RB) is the most common intraocular malignancy in infancy and childhood. This study evaluated the clinical and imaging features, treatment, and prognosis of patients with recurrent RB with limb bone metastases and without central nervous system involvement. Patients and Methods: The clinical data of five patients with RB with limb bone metastases who were diagnosed at the Department of Pediatrics in Beijing Tongren Hospital between January 2015 and January 2021 were analyzed retrospectively. Results: Three males and two females were included (seven eyes: four group E and one each of group D, C, and B). The most common symptom was pain. Three patients had bone marrow and lymph node metastases. Three patients had single and two had multiple skeletal lesions. The main bones that were involved were the femur, humerus, talus, and ulna. The simultaneous involvement of the bone marrow and cortex was also observed. Serum neuron-specific enolase (NSE) levels were significantly elevated in four cases and slightly elevated in one case; primary intravenous chemotherapy resulted in a decrease in NSE levels and the gradual resolution of the bone lesions. Two patients died at the time of follow-up and three were in complete remission. The results of the statistical analysis showed that anterior chamber invasion was correlated with prognosis, and there was significant difference in the decrease in the serum NSE levels after intravenous chemotherapy. Conclusion: Regular lifelong follow-up of patients with RB is warranted to identify bone metastases earlier. Anterior chamber invasion may be a risk factor. The simultaneous involvement of the bone marrow and cortex is characteristic manifestations in images of RB with bone metastases. Multidisciplinary treatment especially intravenous chemotherapy is useful, at least at the beginning.