Liver Metastases : Gross Pathology

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Image Description

Gross Pathology: Liver metastases are usually multiple and form discrete expansive masses or ill-defined infiltrative areas that may greatly enlarge the liver. Larger lesion may undergo central necrosis and fibrosis producing umbilication. Metastatic deposits may be totally buried within the parenchyma and the external surface of the liver may be completely normal. Metastases are frequently gray-white with scattered areas of hemorrhage and necrosis. Individual nodules may be surrounded by areas of venous stasis.

Metastases from highly vascular tumors such angiosarcoma, choriocarcinoma, and thyroid carcinoma are extensively hemorrhagic. Metastatic deposits from colo-rectal cancer may have a fibrous pseudocapsule and frequently undergo calcification if there is copious mucin production. Well-differentiated squamous cell carcinomas produce soft metastases due to necrosis and keratin production. Malignancies of breast, stomach, and pancreas sometimes produce miliary involvement with extremely small lesions scattered throughout the liver. It has been observed in autopsy studies that metastases are very rare in cirrhotic livers. Perhaps, the extensive scarring does not offer a hospitable, nutrient-rich background for the growth of extrahepatic malignancies.

Grossly, many benign lesions can simulate metastases, including fibrous scars, healed granulomas, bile duct hamartoma, and focal nodular hyperplasia. Therefore, gross impression should not form the basis for the diagnosis of metastases by the surgeon intraoperatively or by the pathologist.

The photograph shows liver metastases from a well-differentiated pancreatic neuroendocrine tumor.

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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