LAUSR

© BMJ Publishing Group Limited 2023. No commercial reuse. See rights and permissions. Published by BMJ. CASE DESCRIPTION A young woman in her early 20s, with unremarkable past ophthalmic and family history, presented to the outpatient services with diminution of vision OS since childhood. On clinical exam, the bestcorrected visual acuity was 20/20 OD and 20/200 OS with normal intraocular pressures. Gross examination revealed 30° exotropia OS with unremarkable anterior segment examination on slitlamp biomicroscopy. Fundus examination revealed normal fundus OD (figure 1A) with a welldefined, whitegrey, translucent retinal mass of the posterior pole with feeder vessels, perilesional pigmentary changes and chorioretinal atrophy OS (figure 1B). Autofluorescence imaging revealed normal retinal autofluorescence OD (figure 2A) and a large central area of hypoautofluorescence with a central island of hyperautofluorescence OS (figure 2B). The paternal fundus examination revealed vascular sclerosis and avascularity in the temporal peripheral retina with pigment clump (nonpertinent to the index case) and normal posterior poles OU (figure 3A,B). The maternal fundus examination was unremarkable OU (figure 3C,D). Ocular coherence tomography (OCT) (figure 4) suggested a superficial retinal mass lesion with homogeneous internal reflectivity and occasional intralesional hyporeflective spaces with posterior hyperreflectivity OS. Ultrasonography (figure 5) revealed a corroborating retinal mass lesion of 6.3 mm × 1.8 mm in greatest dimensions with hyperechoic spikes corresponding to intralesional calcification. A clinical diagnosis of retinocytoma was made. The prognosis was explained and the patient continues to be under routine followup. The differential diagnoses to be considered in cases of retinocytoma include retinal astrocytic hamartomas and retinoblastomas. A meticulous clinical examination supplemented with investigations can facilitate differentiation of retinal hamartomas from retinocytomas. A multilobulated domeshaped elevated/semitranslucent flat lesions with lack of pigment epithelial alteration and optically empty spaces on OCT appearance suggests a diagnosis of astrocytic hamartoma. Unfortunately, the only definitive way of differentiating retinocytomas from retinoblastomas are subsequent follow ups for any progressive lesional changes and investigations play little, if any, effect to the same. In their descriptions, Gallie et al described retinocytomas as grey, translucent lesions of the posterior pole with intralesional calcification, pigment epithelial alteration, and areas of chorioretinal atrophy harbouring mutations in both the alleles of the RB1 gene (Rb-/-). 4 The mutated protein, pRb, disrupts the normal checkpoint inhibition of the cell cycle affecting unchecked cell proliferation. Despite the common RB-/genotype as shared with retinoblastomas, retinocytomas are benign, welldifferentiated mass lesions sharing common origins in the retinocyte precursors. 6 The benign nature of these lesions was earlier attributed to a latestage hit of the second allele, varying retention of wildtype protein function, and associated low penetrance. 7–9 Recent genetic analysis of patients with retinocytoma, however, suggests mutated RB1 geneinduced genomic field instability with high expression of senescenceassociated proteins as the mutations underpinning the benign attribute of retinocytoma. Accruing further mutations