Sinusoidal Obstruction Syndrome Following Capeox in Colorectal Cancer: A Diagnostic Challenge

Background: Oxaliplatin, especially when used in combination with capecitabine (CapeOX), is associated with hepatotoxicity, including hepatic sinusoidal injury. Sinusoidal Obstruction Syndrome (SOS) is a rare but potentially serious adverse effect that can complicate chemotherapy regimens for colorectal cancer. Case Summary: We report the case of a 54-year-old woman who developed hepatic dysfunction with jaundice, ascites, and coagulopathy following two cycles of CapeOX as adjuvant chemotherapy for rectal adenocarcinoma. Laboratory investigation revealed AST 1335 U/L, ALT 651 U/L, Total bilirubin7.7 mg/dl and INR 2.49. Extensive workup ruled out viral, autoimmune, and other common etiologies. Transjugular liver biopsy revealed hallmark histopathological features of SOS, including sinusoidal congestion, perisinusoidal fibrosis, and perivenular hepatocyte dropout. Causality assessments using RUCAM (score: 8) and the Naranjo scale (score: 6) indicated a probable chemotherapy-induced liver injury. Prompt discontinuation of the CapeOX regimen and initiation of supportive therapy resulted in clinical and biochemical improvement within one week. Conclusion: This case underscores the need for vigilance regarding hepatic complications in patients undergoing CapeOX chemotherapy. SOS should be considered in patients presenting with unexplained liver enzyme abnormalities, jaundice, or ascites. Early recognition and discontinuation of the offending agents are critical for reversing liver injury and improving outcomes.