Alpha-fetoprotein-producing gastric cancer with ruptured liver metastasis mimicking hepatocellular carcinoma.

Alpha-fetoprotein (AFP)-producing gastric cancer is a rare subtype of gastric cancer known for its aggressive nature. We present an uncommon case of a 60s male with multiple liver tumors, initially suggested as hepatocellular carcinoma (HCC) by imaging. However, a subsequent gastric biopsy revealed a poorly differentiated adenocarcinoma with hepatoid features, and liver biopsy mirrored these findings. The disease progressed swiftly, with the patient representing owing to the spontaneous rupture of a metastatic liver tumor, an extremely rare occurrence, especially in metastatic liver cancers. Such ruptures in AFP-producing gastric cancer may be attributed to the tumor's rich blood flow. Distinctly differentiating this subtype from HCC is pivotal for apt management, as was evident in our case. The diagnosis was particularly challenging due to the similarities in imaging presentations between AFP-producing gastric cancer liver metastasis and HCC. This case underscores the need for vigilant diagnosis, emphasizing the importance of liver biopsy, especially in the absence of chronic liver disease. It also highlights the potential complications, like spontaneous rupture, associated with this rare form of gastric cancer.