Trilateral retinoblastoma: neuroimaging characteristics and value of routine brain screening on admission

Abstract

Trilateral retinoblastoma (TRb) is a rare disease associating intraocular retinoblastoma with intracranial primitive neuroectodermal tumor. Treatment is difficult and prognosis is poor. This multicenter study evaluates clinical findings and MR imaging characteristics of associated intracranial tumors in Rb patients. Clinical data of 17 patients (16 TRb and 1 quadrilateral Rb patients) included time intervals between Rb and TRb diagnosis and presence of baseline brain-imaging (BBI). Two reviewers reviewed all images individually and one reviewer per center evaluated their images. Consensus was reached during a joint scoring session. Studies were reviewed for tumor location, size and imaging characteristics (signal intensity (SI) on T1- and T2-weighted images, enhancement pattern and cystic appearance). Of 18 intracranial tumors, 78 % were located in the pineal gland and 22 % suprasellar. All tumors showed well-defined borders with mostly heterogenous enhancement (72 %) and isointense SI on T1- (78 %) and T2-weighted images (72 %) compared to gray matter. The majority of pineal TRbs showed a cystic component (57 %). TRb detected synchronously with the intraocular tumors on BBI (n = 7) were significantly smaller (P = 0.02), and mainly asymptomatic than TRb detected later on (n = 10). Overall, 5-year-survival of TRb patients detected on BBI was 67 % (95 % CI 29-100 %) compared to 11 % (95 % CI 0-32 %) for the group with delayed diagnosis. TRb mainly develops in the pineal gland and frequently presents with a cystic appearance that could be misinterpreted as benign pineal cysts. Routine BBI in all newly diagnosed Rb patients can detect TRb at a subclinical stage.

Fig. 1

Solid pineoblastoma with hydrocephalus and extensive leptomeningeal metastases. Sagittal T1-weighted (a), axial T2-weighted (b), contrast-enhanced sagittal T1-weighted images of the brain (c) and spine (d) of patient 13. Pineoblastoma showed mostly isointense SI on both T1-weighted (a) and T2-weighted (b) MR images with respect to gray matter and homogenous contrast-enhancement (c). The large tumor mass (33 mm) showed compression on the brainstem (mesencephalon) and cerebral aquaduct (a, c) with secondary hydrocephalus (b). Multiple nodular leptomeningeal tumor seedings are present in the spinal canal (d)

Fig. 2

Suprasellar and pineal gland trilateral retinoblastoma. Contrast-enhanced axial T1-weighted images showing solid tumor masses with cystic components in both the suprasellar region (patient 15) (a) and pineal gland (patient 7) (b). The pineal gland mass causes a secondary hydrocephalus because of brainstem compression (b)

Fig. 3

Pineoblastoma presenting as suspicious cyst. Contrast-enhanced sagittal (a–c) and axial (d) T1-weighted images of the brain in patient 6 (a, b) and patient 16 (c, d). The pineal gland in a shows an irregular cyst wall with tiny nodules, which progressed into a solid tumor with diffuse (nodular) leptomeningeal metastases 14 months later after treatment refusal (b). The pineal gland in patient 16 mimics a pineal cyst on the sagittal image (c), but shows a solid part of the lesion on the axial image (d), suspicious for pineoblastoma