Involution of enhancing intrinsic rectal tumors after endoscopic third ventriculostomy - Report of two cases

For benign intrinsic rectal tumors causing triventricular obstructive hydro cephalus, cerebrospinal fluid diversion followed by neuroimaging is a widel y accepted treatment plan. In this report, the authors describe two childre n with focal enhancing rectal lesions that caused acute, symptomatic hydroc ephalus. One child had neurofibromatosis Type 1 (NF1). In both children the hydrocephalus was effectively treated by endoscopic third ventriculostomy. Following this procedure, serial imaging studies revealed not only that th e ventriculomegaly had resolved, but also that the enhancing tectal tumors had regressed and disappeared over time. The time to complete involution of these tumors was 18 months for the child with NF1 and 12 months for the ot her child. To the authors' knowledge, this is the first report of the invol ution of enhancing rectal tumors after endoscopic third ventriculostomy. Th e possible mechanisms for this unexpected result are discussed.