A 6-month-old boy is brought to the clinic for routine care. He cannot sit with support, and his mother is concerned that his head is large for his age. For the last week, the patient has napped more frequently and vomited at the end of sleep. Height and weight are at the 25th percentile. Head circumference is at the 95th percentile (increased from the 50th percentile at birth and the 75th percentile at age 4 months). The anterior fontanelle is bulging. MRI of the head is shown in the image below: Which of the following is the most likely cause of this patient's condition?

Question

A 6-month-old boy is brought to the clinic for routine care.  He cannot sit with support, and his mother is concerned that his head is large for his age.  For the last week, the patient has napped more frequently and vomited at the end of sleep.  Height and weight are at the 25th percentile.  Head circumference is at the 95th percentile (increased from the 50th percentile at birth and the 75th percentile at age 4 months).  The anterior fontanelle is bulging.  MRI of the head is shown in the image below:  Which of the following is the most likely cause of this patient's condition?

Quizplus · Accepted Answer

11ec25c8_d5ab_691f_bc81_b92a54ed1dfd_MD0003_00 This patient has hydrocephalus with ventriculomegaly (red outline) and an intraventricular mass (blue outline), findings suggestive of a choroid plexus papilloma (CPP). The choroid plexus, a highly vascular, neuroepithelial tissue found within the ventricles, produces cerebrospinal fluid (CSF). Most common in infants, CPP is a rare, slow-growing, benign overgrowth of the choroid plexus that results in increased CSF production. In infants, accumulation of excess CSF (ie, hydrocephalus) causes enlarging head circumference and signs of increased intracranial pressure (eg, poor feeding, bulging fontanelle, irritability, vomiting on waking), as seen in this patient. Developmental delay (eg, inability to sit with support at age 6 months) is also common in infants, and headaches often occur in older children and adults. With increasing tumor size, obstruction of CSF flow can occur, resulting in acutely increased intracranial pressure. Ultrasound of the head typically reveals enlarged ventricles with an intraventricular mass, and MRI confirms the diagnosis. The treatment for a large or symptomatic CPP is resection, and recurrence is rare. (Choice A) Congenital atresia of the foramina of Luschka and Magendie prevents CSF outflow into the subarachnoid space, causing hydrocephalus. This congenital anomaly is associated with Dandy-Walker syndrome, not an intraventricular mass. (Choice B) Increased pressure in the venous sinuses due to dural sinus thrombosis can impair CSF absorption and lead to hydrocephalus. Most patients with dural sinus thrombosis are adults with a prothrombotic risk factor (eg, pregnancy, antithrombin deficiency). In addition, an intraventricular mass would not be seen on imaging. dural sinus (Choice C) Generalized cerebral edema can occur with untreated, worsening hydrocephalus because increased hydrostatic pressure allows CSF to flow into the parenchyma. However, imaging would show flattened gyri and sulci, which are not seen here. cerebral edema (Choice E) In children, nontraumatic intraparenchymal hemorrhage is typically caused by a ruptured arteriovenous malformation and presents acutely with focal neurologic deficits and signs of increased intracranial pressure. An irregular, hyperdense fluid collection within the brain parenchyma, not a well-circumscribed intraventricular mass, would be seen on imaging. intraparenchymal hemorrhage Educational objective: Choroid plexus papilloma is a benign intraventricular mass that causes increased production of cerebrospinal fluid, leading to ventriculomegaly and hydrocephalus. In infants, hydrocephalus presents with enlarging head circumference and signs of increased intracranial pressure. References: Choroid plexus papilloma. (http://www.ncbi.nlm.nih.gov/pubmed/30969571)

A 6-Month-Old Boy Is Brought to the Clinic for Routine