A 2-month-old boy is brought to the clinic for irritability, poor feeding, and frequent vomiting. Weight is at the 15th percentile, and head circumference is at the 96th percentile. Lung sounds are clear throughout, and heart auscultation reveals no murmurs. The abdomen is soft and nondistended. There is hepatosplenomegaly. Diffusely reduced muscle tone is present in all extremities. Funduscopy reveals white-yellow chorioretinal lesions in both eyes. MRI of the brain shows enlarged ventricles and scattered intracranial calcifications. Which of the following is the most likely cause of this patient's condition?

Question

A 2-month-old boy is brought to the clinic for irritability, poor feeding, and frequent vomiting.  Weight is at the 15th percentile, and head circumference is at the 96th percentile.  Lung sounds are clear throughout, and heart auscultation reveals no murmurs.  The abdomen is soft and nondistended.  There is hepatosplenomegaly.  Diffusely reduced muscle tone is present in all extremities.  Funduscopy reveals white-yellow chorioretinal lesions in both eyes.  MRI of the brain shows enlarged ventricles and scattered intracranial calcifications.  Which of the following is the most likely cause of this patient's condition?

Quizplus · Accepted Answer

11ec160b_3886_c40f_9249_a5671889b9d1_MD0001_00 This patient with hydrocephalus, intracranial calcifications, and chorioretinitis has the classic triad of findings for congenital toxoplasmosis. Congenital infections (eg, TORCH infections [Toxoplasmosis, Other infections, Rubella, Cytomegalovirus, and Herpes simplex]) are acquired in utero due to transplacental transmission from an infected mother. Maternal infection may be asymptomatic or mild but can severely affect the fetus, particularly when contracted early in pregnancy. Prolonged inflammation of the CNS during fetal development can lead to chronic inflammatory findings such as intracranial calcifications. Obstructive hydrocephalus can also occur, as seen in this patient with ventriculomegaly, enlarged head circumference, and signs of increased intracranial pressure (eg, vomiting, hypotonia). Chronic chorioretinal inflammation (ie, chorioretinitis) produces white-yellow retinal scars that are visible on funduscopy. Other nonspecific findings that may raise suspicion for in utero infection include growth restriction, hepatosplenomegaly (due to fetal reticuloendothelial activation), and rash. (Choices A and E) Although chromosomal abnormalities and single gene defects can lead to congenital disorders associated with neurologic abnormalities, chorioretinitis is highly associated with infection, particularly when presenting with the classic triad of features for toxoplasmosis. (Choice B) Intrapartum transmission of certain bacteria (eg, group B Streptococcus) or viruses (eg, herpes simplex virus) can cause meningitis or encephalitis beyond the neonatal period, and presentation can include irritability, poor feeding, vomiting, and hypotonia. However, fever would be expected, and chorioretinal lesions would not be seen. (Choice D) Postpartum infection with pathogens such as Toxoplasma and cytomegalovirus is often asymptomatic or can cause mild, self-limited fever, rash, and lymphadenopathy. Late findings of prolonged infection and inflammation (eg, intracranial calcifications, chorioretinitis) typically occur only with intrauterine infection. Educational objective: Congenital toxoplasmosis is an infection acquired in utero that can present with hydrocephalus, intracranial calcifications, and chorioretinitis due to prolonged CNS inflammation.

A 2-Month-Old Boy Is Brought to the Clinic for Irritability