S5847 Hepatopancreatic-Intestinal Malformation With Possible Agenesis of Hepatic Segment IV: Incidental Findings in a 19-Year-Old Male Receiving Methotrexate Therapy

Introduction: The combined hepatopancreatic and interstitial malformation is very rare. This case report describes an incidental finding of such malformation in a 19-year-old man who was on methotrexate therapy for psoriasis. Case Description/Methods: A 19-year-old man with chronic plaque psoriasis on low-dose methotrexate underwent a contrast-enhanced computed tomography (CECT) abdomen for suspected hepatotoxicity following nonspecific abdominal pain, abnormal liver function tests, and an inconclusive abdominal ultrasound. Imaging revealed possible agenesis of segment IV of the liver, with an unusual anterior gap between the right and left hepatic lobes. The left lobe appeared enlarged and located in the left hypochondrium due to possible compensatory hypertrophy of segments II and III. The gallbladder was located within the widened anterior space. The absence of the pancreatic tail along with the distal body near the splenic hilum may suggest partial dorsal pancreatic agenesis. Small bowel loops were predominantly located on the right side of the abdomen, with some loops extending to the right dome of the diaphragm. The cecum and ileocecal junction were located on the right hypochondrium instead of the right iliac fossa. Liver function tests were initially abnormal during methotrexate therapy. Following discontinuation of methotrexate due to these incidental findings, liver enzymes normalized within 8 months. Discussion: This case presents a rare combination of hepatic, pancreatic, and intestinal anomalies, including possible agenesis of segment IV of the liver, which results in an apparent deficiency in the expected hepatic parenchyma medial to the falciform ligament. Associated dorsal pancreatic and intestinal malposition, along with gallbladder location, suggest disrupted foregut rotation and development during embryogenesis. In our patient, the left lobe of the liver is possibly wrapping around the spleen, which could suggest beaver tail liver anomaly; however, there is a large hypertrophied left lobe instead of an extending tail from the left lobe in our case, which might be an atypical variant of it. Segment IV agenesis and beaver tail liver may mimic lobar atrophy, post-inflammatory changes, and traumatic injury to the spleen, respectively. Differentiating such anomalies is essential for accurate diagnosis and management planning. Despite 2 years of normal liver function tests, physicians are withholding methotrexate due to concerns over potential hepatotoxicity in the setting of these rare findings.