Cyst s of pineal gland in retinoblastoma: what link with disease and treatments ?

OBJECTIVES. Retinoblastoma (Rb) represents the most frequent intraocular paediatric tumor, with an average incidence of 1:14'000 to 1:34'000 births. In 2006 we were first to report on pineal cysts that appeared to be more common in children with hereditary bilateral Rb. The aim of our study was to review in a larger patient cohort the occurrence of pineal cysts and to study the link with disease characteristics and treatments received. METHODS AND PATIENTS. Observational retrospective study of clinical and radiological data of 103 patients treated for Rb who had undergone a cerebral magnetic resonance imaging (MRI) between 2006 and 2013 and had a follow-up. Clinical records were reviewed for sex, age at diagnosis, hereditary pattern of disease, tumor laterality, stage according to the International Classification of Retinoblastoma, age at first MRI, treatments received, date of first and last treatment and last follow-up, response to treatment, long-term outcome, time interval from diagnosis of Rb to the diagnosis of a pineal cyst, and genetic data if known. Radiological reports and brain images were reviewed for each patient with pineal cyst to record its size and change over time. RESULTS. Of 103 patients with Rb 56 had unilateral and 47 bilateral disease. Ninety-five were sporadic Rb while 8 were familial. Forty-nine MRIs out of 103 (47.6%) presented a pineal cyst and were reviewed by a neuroradiologist to verify aspect and the size of the pineal gland. Occurrence of cysts was more frequent in bilateral disease, sporadic disease, in presence of a documented genetic mutation and in group D or E, but without statistically significance. No impact of treatment on the occurrence of cysts could be demonstrated. At 1 year of follow-up, cysts had higher growth in bilateral Rb and those with documented genetic mutation, but without statistical significance. None of the other parameters showed significant impact on growth. CONCLUSIONS. We found a high incidence of pineal cysts in Rb patients, but could not demonstrate a significant relationship to the hereditary subgroup or genetic mutation. The evolution was benign without malignant transformation in absence of atypical radiological signs. The higher incidence however compared to a healthy paediatric population clearly indicates that pineal cysts are part of the disease-related midline brain abnormalities