Right-lobe hepatic mucinous cystic neoplasm with an adjacent large hemorrhagic-appearing cyst: Markedly elevated serum CEA and CA19-9 despite benign imaging/pathology

Mucinous cystic neoplasm (MCN) is a multilocular cystic mass that most commonly develops in the pancreas, whereas its occurrence in the liver is relatively rare and typically involves the left lobe. We report a case of right-lobe hepatic MCN in a woman in her 60s, accompanied by markedly elevated serum CEA and CA19-9 levels and an adjacent large hemorrhagic-appearing cyst. Contrast-enhanced CT demonstrated a 10-cm multilocular cystic tumor with a cyst-in-cyst configuration, gradual septal enhancement, partial septal calcification, and no enhancing mural nodules. MRI demonstrated a stained glass–like appearance with no diffusion restriction. She underwent right hepatic lobectomy with diaphragmatic resection, and pathological examination confirmed MCN with ovarian-like stroma without malignant transformation. The postoperative course was uneventful. Serum levels of CEA and CA19-9 normalized one month postoperatively, and no recurrence has been observed during follow-up. When a multilocular cystic mass with cyst-in-cyst morphology and a stained glass–like appearance is identified in the liver—even in the absence of definite malignant imaging features—MCN should be considered, including in cases arising in the right hepatic lobe.