A “Hot” Sulfur Colloid Clue in a Hypervascular Pediatric Liver Mass

Focal nodular hyperplasia (FNH) in young children may mimic malignancy when large and markedly hypervascular. A 5-year-old girl with no known predisposing factors presented with painless abdominal distension and hepatomegaly. Serum alpha-fetoprotein and beta-human chorionic gonadotropin were normal. MRI showed a hypervascular hepatic mass with stellate central scar, abnormal intralesional vessels, and intrahepatic arteriovenous shunting, concerning for fibrolamellar hepatocellular carcinoma (FLHCC). Subsequent ⁹⁹ᵐTc-sulfur-colloid scintigraphy demonstrated near-homogeneous tracer uptake within the lesion, mildly lower than the normal liver. The preserved Kupffer-cell function favored FNH, likely arising as a hyperplastic response to altered local perfusion. Clinical surveillance supported the benign diagnosis.