Two case reports of breast cancer combined with synchronous primary intrahepatic cholangiocarcinoma/mixed liver cancer.

RATIONALE: This case report discusses multiple primary malignant tumors, which refer to the occurrence of 2 or more different histological types of malignant tumors simultaneously or successively in the same individual.

PATIENT CONCERNS: We present 2 female patients who were admitted to the hospital due to a "left breast mass" and were found to have multiple solid masses in the liver upon imaging.

DIAGNOSES: Postoperative pathology revealed that one patient had breast invasive ductal carcinoma was complicated with primary intrahepatic cholangiocarcinoma and mixed hepatocellular carcinoma with intrahepatic cholangiocarcinoma.

INTERVENTIONS: Both patients underwent extensive resection of the lesion.

OUTCOMES: Regular postoperative checkups and follow-ups have been conducted, and both patient's current conditions are stable.

LESSONS: The treatment approach adopted in this case report may serve as a favorable reference for the management of similar cases. However, further extensive biological studies are still needed to investigate the biological mechanisms of multiple primary malignant tumors and to discover specific therapeutic approaches to achieve more clinical benefits for patients.