Pineal cysts and other pineal region malignancies: determining factors predictive of hydrocephalus and malignancy.

OBJECTIVE Cystic lesions of the pineal gland are most often uncomplicated benign lesions with typical MRI characteristics. The authors aimed to study pineal lesion characteristics on MRI to better distinguish benign pineal cysts from other pineal region malignancies as well as to determine which characteristics were predictive of the latter malignancies. They also aimed to study risk factors predictive of hydrocephalus or malignancy in patients harboring these lesions. METHODS The authors performed a retrospective review of a prospectively compiled database documenting the outcomes of patients with suspected pineal cysts on MRI who had presented in the period from 1998 to 2004. Inherent patient and lesion characteristics were assessed in a univariate logistic regression analysis to predict the following dependent variables: development of hydrocephalus, biopsy-confirmed malignancy, and intervention. Possible inherent patient and lesion characteristics included age, sex, T1 and T2 MRI signal pattern, contrast enhancement pattern, presence of cyst, presence of blood, complexity of lesion, presence of calcification, and duration of follow-up. Inherent patient and lesion characteristics that were predictive in the univariate analysis (p < 0.15) were included in the multivariable logistic regression analysis. RESULTS Of the 79 patients with benign-appearing pineal cysts, 26 (33%) were male and 53 (67%) were female, with a median age of 38 years (range 9-86 years). The median cyst radius was 5 mm (range 1-20 mm). Two patients (2.5%) had evidence of calcifications, 7 (9%) had multicystic lesions, and 25 (32%) had some evidence of contrast enhancement. The median follow-up interval was 3 years (range 0.5-13 years). Seven patients (9%) had an increase in the size of their lesion over time. Eight patients (10%) had a hemorrhage, and 11 patients (14%) developed hydrocephalus. Nine (11%) received ventriculoperitoneal shunts for the development of hydrocephalus, and 12 patients (16%) were found to have malignancies following biopsy or resection. In the multivariate analysis, contrast enhancement on MRI (OR 1.6, 95% CI 2.86-74.74, p = 0.013) and hemorrhage (OR 26.9, 95% CI 3.4-212.7, p = 0.022) were predictive of hydrocephalus. Increasing lesion size and hydrocephalus were near perfect predictors of malignancy and thus were removed from multivariate analysis. In addition, contrast enhancement on MRI (OR 8.8, 95% CI 2.0-38.6, p = 0.004) and hemorrhage (OR 6.8, 95% CI 1.1-40.5, p = 0.036) were predictive of malignancy. CONCLUSIONS Although cystic abnormalities of the pineal gland are often benign lesions, they are frequently monitored over time, as other pineal region pathologies may appear similarly on MRI. Patients with growing lesions, contrast enhancement, and hemorrhage on MRI are more likely to develop hydrocephalus and have malignant pathology on histological examination and should therefore be followed up with serial MRI with a lower threshold for neurosurgical intervention.