Clinical and Histopathological Features of Diffuse Infiltrating Retinoblastoma in Chinese Children

Purpose: To describe the clinical and histopathological characteristics of diffuse infiltrating retinoblastoma underwent primary enucleation from Chinese children. Methods: It was a hospital-based retrospective study that included all eyes with retinoblastomas consecutively enucleated in the Beijing Tongren Hospital between October 2005 and October 2019. Further studies were carried out in patients diagnosed by clinicians and pathologists as diffuse infiltrating retinoblastoma. Results: Out of 1,911 patients, 37 eyes of 37 patients (2%) were classified as diffuse infiltrating type and treated with primary enucleation. The tumors were detected at a mean age of 47 months (range: 6–108 months). There were two (5%) patients with binocular tumors and one (3%) patient with a positive family history. Anterior chamber fine needle aspiration biopsy was obtained in 5 cases for diagnostic purpose. In 11 patients (30%), the retinoblastoma had not initially been diagnosed as a tumor. The most common symptoms found on ophthalmic examination were conjunctiva injection (n=17;46%) of anterior segment and vitreous seeds (n=23; 62%) of posterior segment. 12 of 37 tumors measured by imaging examination and cross-section showed the average height was 7mm and average width was 10mm. The minimum tumor diameter was just 3mm. Histopathology revealed tumor invasion into optic nerve (n=26; 70%), iris (n=14; 38%), ciliary body (n=12; 32%), massive choroid (n=2;5%) and iris neovascularization (n=24; 65%). Histopathologic risk factors (HRF) were detected in 26 eyes. Anterior chamber fine needle aspiration biopsy (FNAB), cornea endothelium with tumor seeds, anterior chamber free-floating tumor seeds, or pseudohypopyon might contribute to a higher rate of histopathological risk factors. Conclusions: Diffuse infiltrating retinoblastoma was usually masqueraded as endophthalmitis. Therefore, it should always be considered as a differential diagnosis in intraocular inflammation. Considering the so small diameter of the tumor, it should be examined carefully. Anterior chamber fine needle aspiration biopsy should be used with caution.