A Case of Concurrent Liver Metastases from Colorectal and Breast Cancer Diagnosed Using Percutaneous Tumor Biopsy

Treatment strategies for liver metastases differ according to the primary tumor origin. In patients with multiple primary malignancies, liver tumors should not be assumed to originate from a single cancer. We report a rare case of concurrent liver metastases from colorectal and breast cancer diagnosed using percutaneous tumor biopsy.

A 71-year-old woman was diagnosed with de novo metastatic invasive lobular carcinoma of the left breast with multiple lymph node and bone metastases, but without liver metastases. CDK4/6 inhibitor plus endocrine therapy was initiated as first-line treatment. Although the breast lesion and lymph node metastases decreased, serum carcinoembryonic antigen levels subsequently increased, and a new liver lesion appeared. Further evaluation revealed a stenotic rectosigmoid lesion, and biopsy demonstrated poorly differentiated colorectal adenocarcinoma, supporting primary rectal cancer. Gadoxetic acid-enhanced magnetic resonance imaging revealed multiple bilobar liver tumors with two distinct patterns: small, homogeneously enhancing lesions and larger lesions with peripheral enhancement. Ultrasonography also showed heterogeneous findings, including a homogeneous hypoechoic lesion in segment 5/6 and a target-sign lesion in segment 1. These imaging differences suggested liver metastases from different primary tumors. Percutaneous biopsies followed by needle-tract radiofrequency ablation were performed for two selected lesions. Histological examination confirmed breast cancer liver metastasis in segment 5/6 and colorectal liver metastasis in segment 1.

Heterogeneous imaging findings on magnetic resonance imaging and ultrasonography may suggest different primary origins of liver metastases in patients with multiple malignancies. Percutaneous tumor biopsy with immunohistochemistry is useful for accurate diagnosis and appropriate treatment selection.