Isolated hemihypertrophy in a child with tetralogy of Fallot and brain abscess: A rare co-occurrence.

Isolated hemihyperplasia (IHH) is a rare congenital condition characterized by asymmetric overgrowth of body parts, often associated with increased risk of embryonal tumors. While syndromic forms are well-documented, idiopathic IHH without dysmorphic features remains underrecognized. Tetralogy of Fallot (TOF), a common cyanotic congenital heart defect, and brain abscesses are known complications in cyanotic heart disease, but their co-occurrence with IHH is exceedingly rare. We report a 3-year-old boy presenting with fever, irritability, and limb asymmetry. Clinical examination revealed right-sided hemihyperplasia, cyanosis, and clubbing. Echocardiography confirmed TOF. Neuroimaging identified a left frontoparietal brain abscess. Syndromic causes of hemihyperplasia were excluded based on clinical features. The child responded well to intravenous antibiotics and supportive care. Tumor surveillance was initiated, and cardiac surgical planning was underway. This case highlights a rare triad of IHH, TOF, and brain abscess, not previously reported in the literature. It underscores the importance of thorough phenotypic assessment, tumor surveillance, and multidisciplinary management in complex pediatric presentations.