Brain abnormalities on MR imaging in patients with retinoblastoma

Abstract

Background and purpose: Although pineoblastoma is the main brain abnormality associated with hereditary retinoblastoma, recent studies suggest an association with pineal cysts. This association is important because some pineoblastomas mimic pineal cysts. If there is a relationship, then radiologists should be aware of it because diagnostic confusion is possible. Mental retardation and congenital brain anomalies are also reported in patients with retinoblastoma, mostly in combination with 13q deletion syndrome. In this retrospective study, the presence of brain abnormalities on MR images in a large group of consecutive patients with retinoblastoma is evaluated.

Materials and methods: Brain MR images of 168 patients with retinoblastoma from 1989 to 2009 were evaluated by 2 radiologists for tumors, structural anomalies, myelinization, and coincidental findings. Clinical records were reviewed for laterality, heredity, and the presence of the 13q deletion syndrome.

Results: The hereditary group (patients with bilateral and unilateral proved RB1-germline mutation) included 90 (54%) of 168 patients. Seven patients had 13q deletion syndrome. Normal findings on brain MR images were seen in 150 (89%) patients. Five pineoblastomas were detected, all in patients with hereditary retinoblastoma (5.5% in the hereditary subgroup). Nine pineal cysts were detected (2.2% in the hereditary subgroup). Corpus callosum agenesis was found in 1 patient and a Dandy-Walker variant in 1 patient, both in combination with 13q deletion syndrome.

Conclusions: Pineoblastoma is associated with hereditary retinoblastoma, and structural brain abnormalities are restricted to patients with the 13q deletion syndrome. The incidence of pineal cysts in patients with retinoblastomas is similar to that in healthy children and is not associated with hereditary retinoblastoma.

Fig 1.

Patient 5, a 10-month-old with hereditary retinoblastoma and pineoblastoma. A, Sagittal T1-weighted postgadolinium MR image shows a cystic mass in the pineal gland. B, Axial T1-weighted image shows an asymmetric nodular thickening of the tumor wall. The thickness of the enhancing wall varies from 3 to 7 mm, suspicious for pineoblastoma.

Fig 2.

Patient 10. Contrast-enhanced T1-weighted MR image of a 34-month-old patient with nonhereditary retinoblastoma with a pineal cyst, with a diameter of 7 mm.

Fig 3.

Patient 3. Sagittal T1-weighted image of a 4-month-old with 13q deletion syndrome and bilateral retinoblastoma shows agenesis of the splenium of the corpus callosum.