Abstract and Introduction
Abstract
A variety of mass lesions can arise within or in proximity to the ventricular system in children. These lesions are relatively uncommon, and they present a unique diagnostic and surgical challenge. The differential diagnosis is determined by tumor location in the ventricular system, clinical presentation, age of the patient, and the imaging characteristics of the lesion. In this report the authors provide an introduction to and an overview of the most common pediatric supratentorial intraventricular tumors. The typical radiographic features of each tumor and location preference within the ventricular system are reviewed. Management and treatment considerations are discussed. Examination of tissue samples to obtain diagnosis is usually required for accurate treatment planning, and resection without adjuvant therapies is often curative. The critical management decision frequently involves determining which lesions are appropriate for surgical therapy. Care ful preoperative neuroimaging is extremely useful in planning surgery. Knowledge of the typical imaging characteristics of these tumors can help to determine the diagnosis with relative certainty when a tissue sample has not been obtained, because a small subset of these lesions can be managed expectantly.
Introduction
One tenth of all CNS neoplasms present within or in proximity to the ventricular system. These neoplasms comprise a heterogeneous group with regard to tumor type and clinical prognosis in both children and adults. Although some of these tumors are aggressive high-grade lesions, many are histologically benign and potentially curable by undertaking resection. Because they tend to grow slowly, however, they may remain clinically silent and reach significant size before becoming symptomatic, making the excision technically challenging. Typically, these lesions cause symptoms and signs of increased ICP due to hydrocephalus, which will vary depending on the age of the patient. An older child with raised ICP will complain of persistent headache or have episodes of vom-iting that characteristically occur in the morning. In the nonverbal child or infant, the only evidence of increased ICP may be nonspecific signs of irritability, loss of appetite, anhedonia, or a finding of macrocrania. Specific focal neurological deficits occur depending on tumor location and involvement of adjacent structures or surrounding cerebral parenchyma.
Specific tumor types appear to occur more frequently in certain anatomical locations and in certain age groups. Table 1 provides a list of common pediatric intraventricular tumors by ventricular location. The imaging characteristics of these lesions are also described in Table 2. Although these distinctions may seem arbitrary as most of these tumors occur in patients throughout the ventricular system and across a wide range of ages, tumor location, age of the patient, and imaging characteristics are helpful in determining the differential diagnosis. To make the distinction between intra-and extraventricular lesions also aids in differential diagnosis and guides in planning the surgical approach.
Microsurgical resection has been the treatment of choice for the majority of these lesions. The use of stereotactic navigational systems to assist in volumetric resection of intraventricular tumors has also been described. Minimally invasive neuroendoscopic techniques used to diagnose and potentially resect intraventricular tumors may ultimately prove to be as effective as microsurgical approaches. The propensity of intraventricular tumors to reach significant size at presentation as well as the risk of significant bleeding with piecemeal resection, especially in cases of lateral ventricular tumors limit the role of endoscopic techniques to selected cases. Tumor histological type and location as well as the presence and degree of neurological deficit determine the management in the individual patient.