Focal Hepatic Steatosis Mimicking a Hilar Tumor With Rapid Resolution After Glycemic Control: A Case Report.

Focal hepatic steatosis can present as a mass-like pseudolesion, particularly in segment IV (S4) adjacent to the hepatic hilum, and may raise concern for perihilar malignancy. We report a 56-year-old woman with severe hyperglycemia (random plasma glucose 564 mg/dL; HbA1c 12.4%) in whom ultrasonography and computed tomography revealed a small hilar S4 lesion suspicious for a perihilar tumor. Magnetic resonance imaging demonstrated a prominent signal drop on opposed-phase chemical shift imaging without diffusion restriction and without biliary ductal abnormality on MR cholangiopancreatography, favoring focal steatosis rather than neoplasm. Based on these findings, we prioritized metabolic optimization with short-interval follow-up rather than immediate biopsy. After intensive glycemic control, HbA1c improved to 6.6%, and the lesion completely disappeared within three months, confirmed sequentially on ultrasonography, contrast-enhanced CT, and MRI. This case highlights a practical strategy: when chemical shift MRI supports focal steatosis and ancillary malignant features are absent, metabolic optimization followed by short-interval follow-up imaging can confirm the diagnosis and avoid unnecessary invasive procedures.