Spatiotemporal Patterns of Intraocular Tumor Occurrence in Children with Retinoblastoma

Abstract

 

Purpose

 

To map the spatial distribution and foci of origin of intraocular retinoblastoma at the time of diagnosis in a prospectively enrolled patient cohort.

 

Methods

 

Orbital MRI in 98 consecutive retinoblastoma patients(39 bilateral) was analyzed in axial, coronal and sagittal imaging planes(Syngo Viewer, Siemens AG, Germany). The central visual axis was approximated relative to the optic nerve and the polar angle and visual angle of eccentricity were measured for a series of points along each tumor margin. The tumor outline was interpolated on a polar coordinate system centered at the fovea. Tumor maps were digitized and the centroid of the mapped area was calculated to approximate tumor focus of origin.

 

Results

 

Eyes were excluded from mapping(31) for globe filling disease or inadequate tumor visualization on MRI. Mapping failed in some eyes(21) secondary to extensive retinal detachment and vitreous seeding. Mapping was successful for 178 tumors in 85 eyes from 63 patients(35 bilateral). Cumulative tumor burden was highest within the macula and posterior pole and was asymmetrically higher within the ventral and nasal hemiretinas(Fig. 1). Tumor location varied with age at diagnosis(Fig. 2). Tumor occurrence in patients <6 months was highest within the macula and superonasal periphery. Most tumors diagnosed at 6-9 months were in the inferotemporal quadrant of the posterior pole. Tumor occurrence shifted into the inferonasal quadrant in patients 9-16 months and extended diffusely throughout the nasal periphery in patients >16 months. Clinical information for 38 of the unmapped tumors showed that only 5 (13%) involved the superotemporal quadrant, consistent with the asymmetry of mapped tumors.

 

Conclusions

 

Precise mapping of tumor on the retina revealed a complex spatial pattern of occurrence which evolves with age. The spatiotemporal distribution of tumors may provide valuable clues regarding the cell of origin, the developmental context that facilitates tumorigenesis, and the impact of disease on vision in children with retinoblastoma.

 

 

Cohort cumulative tumor burden over the mapped the retina. Left eye nasal-temporal coordinates were inverted, color indicates number of tumors.

 

 

Distribution of tumor centroids. A) Location by laterality (triangle=bilat), area (size= quartiles), and age (young-to-old quartile=pink, orange, blue, green) B) Estimated tumor density relative to a uniform density over the mapped retina.

 

Keywords: 703 retinoblastoma • 550 imaging/image analysis: clinical