Liver Metastases : Introduction

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Introduction: Liver is one of the most frequent sites for metastatic spread of tumors. Autopsy studies have shown that liver metastases occur in 40% to 50% of adults dying of cancer. Metastases are far more common than primary hepatic malignancies in non-cirrhotic livers in Western countries.

Pathogenesis: Liver is a particularly receptive organ to metastases from many sites due to its dual blood supply (hepatic and portal). The sinusoidal epithelium has fenestrations which allow malignant cells to escape circulation and enter liver parenchyma. Liver is often the sole site of metastatic disease.

The predominant histologic subtypes are adenocarcinomas, squamous cell carcinomas, and neuroendocrine carcinomas. Primary Sites: ADULTS: The most common metastatic tumors in the liver are derived from primary cancers of the gastrointestinal tract and pancreas which drain into the liver via portal circulation. In addition, malignancies of lung, breast, kidney, malignant melanomas, lymphomas and soft tissue sarcomas also frequently metastasize to liver. Primary malignancies of gall bladder, extrahepatic bile ducts, stomach, and pancreas can involve liver by direct extension. CHILDREN: The most common primary sites in children are neuroblastoma, Wilms tumor, and rhabdomyosarcoma.

This photograph shows liver metastases from small cell carcinoma of lung.

About the Disease

Metastasis is the most common malignancy in non-cirrhotic livers in the Western countries. About 40%-50% of patients dying from cancer have liver metastases. Liver is highly susceptible due to dual blood supply (hepatic and portal) and fenestrations in sinusoidal epithelium which allow tumor cells to escape into the parenchyma. Primary sites in adults: pancreas, stomach, colon, lung, breast, kidney, malignant melanomas, and soft tissue sarcomas. Malignancies of gall bladder, extrahepatic bile ducts, stomach, and pancreas can spread to liver by direct extension. Primary sites in children: neuroblastoma, Wilms tumor, and rhabdomyosarcoma. Presentation ranges from no symptoms to fulminant hepatic failure. Patients may develop malaise, anorexia, weight loss, abdominal pain, and obstructive jaundice. Diagnosis can be accurately made in most cases by CT- or ultrasound guided-FNA and needle core biopsies. Metastases form multiple, discrete expansive masses or ill-defined infiltrative areas. Larger nodules undergo necrosis and fibrosis producing umbilication. Liver may be greatly enlarged with an irregular surface. Malignancies of breast, stomach, lung, pancreas, and lymphomas may produce miliary involvement. Metastases are quite rare in cirrhotic livers. Microscopic features are those of the primary tumor. Metastatic adenocarcinomas may invade bile ducts and show intrabiliary growth mimicking cholangiocarcinoma. Prognosis is poor in most cases (with some exceptions). Most patients die within 1 year of presentation. Resection of isolated liver metastases from colo-rectal cancers can produce long-term disease-free survival or even cure in some cases. Patients with liver metastases from neuroendocrine tumors and Carcinoid syndrome get dramatic relief from symptoms after resection of metastatic foci. References: 1. Iacobuzio-Donahue, C. A. & Montgomery E. (2012). Gastrointestinal and Liver Pathology - 2nd Edition. Philadelphia, PA. Elsevier Saunders. 2. Feldman, M., Friedman, L. S., & Brandt, L. J. (2016). Sleisenger & Fordtran's Gastrointestinal & Liver Disease - 10th Edition. Philadelphia, PA. Elsevier Saunders. 3. Goldblum, J. R. et al (2018). Rosai and Ackerman's Surgical Pathology - 11th Edition. Philadelphia, PA. Elsevier.4. DeVita, V. T., Lawrence, T. S., & Rosenberg, S. A. (2019). Cancer - Principles & Practice of Oncology - 11th Edition. Wolters Kluwer.

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