LAUSR

Question: A 32-year-old woman with no past medical history presented to our medical center with 2 months of intermittent right upper quadrant pain. The pain started gradually, hurting primarily when lying on her right side. She had limited past medical history and denied any current medications. Examination revealed mild tenderness to her right upper quadrant without palpable masses. Laboratory data were within reference values. Cross-sectional imaging (Figure A, B) demonstrated a cystic mass arising in the right retroperitoneum measuring 6.0 8.1 cm. The mass was abutting the right hemidiaphragm with some loculation and abutting the caudate lobe of the liver and inferior vena cava. Given the location and complexity of the mass subsequent endoscopic ultrasound-guided fine needle aspiration biopsy was performed (Figure C) demonstrating a large, 6.5 8.7 cm cyst adjacent to the left lobe of the liver. The cyst was anechoic. There were a few internal septations. The outer wall of the lesion was thin and irregular, with a few areas of thickening. There seemed to be a moderate amount of debris within the cyst cavity. Diagnostic needle aspiration for fluid was performed. The fluid was clear and viscous. The amylase was 35 and carcinoembryonic antigen 19,344; the cytology demonstrated no evidence of malignancy. Given her ongoing symptoms, the size of the lesion, and premalignant nature of mucinous cysts, the decision was made to pursue surgical resection. What is the diagnosis? See the Gastroenterology web site (www.gastrojournal.org) for more information on submitting your favorite image to Clinical Challenges and Images in GI.