Abstract
Purpose :
Retinocytoma is the benign equivalent of retinoblastoma (RB) diagnosed by lack of growth and the classic triad of translucent mass, calcification and retinal pigment epithelial (RPE) changes. Presence of retinocytoma is definitive evidence of presence of the RB1 gene with same genetic implications as RB. This study assesses the multimodal imaging (MMI) features of these rare tumors.
Methods :
This was a retrospective case series of all retinocytomas diagnosed at a tertiary ophthalmic institute in India from 2015-2020. 12 tumors in 11 eyes of 10 patients were included. MMI performed were color fundus photography (CFP), autofluorescence, USG B-scan, ultra-widefield imaging, fundus fluorescein angiography (FFA), swept-source OCT and OCTA. Demographic features, laterality and history of RB was recorded. Clinical characteristics, largest basal dimension and location were documented for each tumor. Qualitative analysis of retina and choroid on OCT and OCTA was performed. At each visit, the tumor was documented as stable, progressing or regressing.
Results :
The median age was 11.5 years and 80% were males. A family history of retinoblastoma was present in 20%. 1 patient had bilateral involvement. 5 patients (45.45%) were asymptomatic. Translucent mass, calcification and RPE changes were noted in 67%, 50% and 75% of tumors. 67% also had chorioretinal atrophy (CRA). A superficial hyperreflective layer was found in 100% of eyes that underwent OCT, corresponding to retinal nerve fibre layer (RNFL). In 50% of these, inner retinal layers (IRL) were further discernible. OCT angiography showed choriocapillaris loss with intact SCP and DCP. During a mean follow-up of 5 years, none of the tumors exhibited growth or malignant transformation.
Conclusions :
Preliminary neurosensory retinal differentiation in retinocytomas is a novel finding that has not been previously reported. In this study, among tumors that underwent OCT, RNFL was identified in 100% and additional IRL in 50%. These findings prove that retinocytomas arise de novo and are not spontaneously regressed RB. Retinoblastomas have full-thickness retinal replacement with disorganized tissue on OCT. In clinically ambiguous cases, presence of preserved retinal layers on OCT can be used to distinguish retinocytomas from RB. Thus, MMI provides new insights into the pathology and natural history of retinocytomas and is an excellent tool for serial monitoring.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.