Left triangular ligament lesions are likely hepatic in origin

OBJECTIVES: The left lobe of the liver is connected to the left hemi-diaphragm by the left triangular ligament (LTL) which crosses the left upper quadrant (LUQ) of the abdomen. LTL lesions are rare and can cause diagnostic confusion. We encountered a hepatocellular carcinoma in the LTL of one patient and given that the LTL has been shown to contain liver tissue in cadaveric studies, we hypothesise that LTL lesions are likely hepatic in origin. The aim of this case series and systematic review was to develop a list of pathological processes encountered at the LTL, which could impact differential diagnoses of lesions within the LUQ. METHODS: A case series of two patients are presented. MEDLINE, EMBASE, PubMed, and Google Scholar were searched for studies published until September 2022. All case reports of LTL lesions were eligible for inclusion. PROSPERO registration: CRD42022368250. RESULTS: Twelve out of 166 screened studies were included, with 14 cases in total. Seven described mass lesions of hepatic origin, of which three were initially misdiagnosed as gastric tumours leading to considerable diagnostic delay and additional procedures. Seven other cases described postoperative bile leaks from aberrant biliary ducts in the LTL. CONCLUSIONS: All mass lesions observed in the LTL were hepatic in origin, and all iatrogenic injuries described resulted in bile leaks. ADVANCES IN KNOWLEDGE: To reduce the burden of diagnostic delay and unnecessary procedures, we would suggest that these observations support the addition of hepatic lesions to the differential diagnosis of LUQ lesions.