Metastatic GIST

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Image Description

Gastrointestinal stromal tumors and leiomyosarcomas are the most frequent sarcomas to metastasize to the liver. With GIST, FNA smears show relatively monomorphic spindle cells arranged singly or in small aggregates. The background may show myxoid stroma.

With epithelioid GIST, the differential diagnosis includes melanoma, carcinoma, and neuroendocrine tumors. Needle core biopsies will show sheets of plump epithelioid cells with eosinophilic cytoplasm. Classic GISTs show high vascularity, paranuclear vacuoles, variably myxoid or hyalinized stroma, and sometimes skenoid fibers (extracellular collagen globules). Immunohistochemical analysis shows positivity for CD117, DOG1, CD34, and vimentin. SMA, cytokeratins, and S-100 are variably positive. Desmin is negative.

This gross specimen photograph of a liver slice is from a young female patient with history of GIST of stomach. Two years after gastrectomy she presented with liver metastases. There are several tumor nodules with hemorrhage and necrosis. Image copyright: pathorama.ch.

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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