Correct Answer: C. Congenital cytomegalovirus infection
Congenital cytomegalovirus (CMV) infection is the most common congenital viral infection in India and worldwide, affecting 0.5–1% of live births. The clinical triad of hepatosplenomegaly, thrombocytopenia, and periventricular calcifications on neuroimaging is pathognomonic for congenital CMV. These periventricular calcifications represent areas of ventriculitis and necrosis along the ventricular walls, a hallmark finding that distinguishes CMV from other TORCH infections. CMV causes direct cytopathic damage to developing neural tissue, leading to microcephaly, ventriculomegaly, and these characteristic calcifications. The thrombocytopenia results from bone marrow suppression and immune-mediated destruction. Hepatosplenomegaly occurs due to extramedullary hematopoiesis and direct viral invasion of hepatocytes. Unlike rubella (which causes cataracts and cardiac defects) or toxoplasmosis (which causes intracranial calcifications but typically in basal ganglia and cortex), CMV's periventricular location is distinctive. Congenital CMV may present with asymptomatic infection (90% of cases) or symptomatic disease with microcephaly, sensorineural hearing loss, developmental delay, and chorioretinitis. Diagnosis is confirmed by CMV PCR from urine or saliva within the first 3 weeks of life. Indian pediatric guidelines recommend screening high-risk pregnancies and early antiviral therapy (ganciclovir or valganciclovir) for symptomatic congenital CMV to prevent progressive hearing loss and neurodevelopmental sequelae.
Why the other options are wrong
A. Congenital herpes simplex virus infection — HSV typically presents with vesicular rash, keratoconjunctivitis, and disseminated disease (hepatitis, encephalitis) rather than the isolated triad of hepatosplenomegaly, thrombocytopenia, and periventricular calcifications. Neuroimaging in HSV shows temporal lobe involvement and diffuse encephalitis, not periventricular calcifications. HSV is also less common as a congenital infection compared to CMV in the Indian population. B. Congenital toxoplasmosis — While toxoplasmosis does cause hepatosplenomegaly and thrombocytopenia, its characteristic intracranial calcifications are scattered throughout the brain parenchyma (basal ganglia, cortex, white matter) rather than periventricular. Toxoplasmosis classically presents with chorioretinitis ('pizza pie' retinopathy), which is absent in CMV. Toxoplasmosis is also less common in India due to lower seroprevalence of Toxoplasma gondii compared to developed nations. D. Congenital rubella syndrome — Rubella causes the classic triad of cardiac defects (patent ductus arteriosus, pulmonary stenosis), cataracts, and sensorineural hearing loss—not periventricular calcifications. Rubella may cause hepatosplenomegaly and thrombocytopenia ('blueberry muffin' rash), but neuroimaging findings are nonspecific (microcephaly, encephalitis) without the distinctive periventricular calcification pattern seen in CMV.
High-Yield Facts
- Periventricular calcifications on CT/MRI are pathognomonic for congenital CMV and distinguish it from other TORCH infections.
- Congenital CMV is the most common congenital viral infection (0.5–1% of live births) and the leading preventable cause of sensorineural hearing loss in children in India.
- 90% of congenital CMV infections are asymptomatic at birth; symptomatic disease includes microcephaly, ventriculomegaly, chorioretinitis, and developmental delay.
- CMV diagnosis requires PCR from urine or saliva within the first 3 weeks of life to confirm congenital infection (not postnatal acquisition).
- Ganciclovir or valganciclovir is the DOC for symptomatic congenital CMV; early treatment (within 30 days of birth) reduces hearing loss progression by ~50%.
- Thrombocytopenia in congenital CMV is due to bone marrow suppression and direct viral invasion, resulting in platelet counts often <50,000/μL in severe cases.
Mnemonics
TORCH Calcifications Toxo = scattered (basal ganglia); Other (rubella) = nonspecific; Rubella = cardiac; CMV = periventricular; HSV = temporal lobe. Use this to recall that CMV's calcifications are periventricular, not scattered like toxo. CMV Triad in Congenital Infection Hepatosplenomegaly, Thrombocytopenia, Periventricular calcifications = HTP sign for congenital CMV. When you see this triad on imaging, think CMV first.
NBE Trap
NBE may pair hepatosplenomegaly + thrombocytopenia with toxoplasmosis (which also causes these findings) to lure students who forget that toxoplasmosis calcifications are scattered throughout brain parenchyma, not periventricular. The periventricular location is the discriminating feature.
Clinical Pearl
In Indian neonatal units, congenital CMV is often missed because 90% of infected infants appear asymptomatic at birth. Universal newborn screening for CMV (via PCR from dried blood spots) is not yet standard in India, but high-risk infants (born to seronegative mothers with primary CMV infection during pregnancy) should undergo urine CMV PCR within 3 weeks of life to enable early antiviral therapy and prevent permanent hearing loss.
_Reference: OP Ghai Essentials of Pediatrics Ch. 5 (Neonatology & Congenital Infections); Harrison Principles of Internal Medicine Ch. 165 (Cytomegalovirus)_