Primal hepatic carcinoma - hepatocellular/cholangiocellular. Etiology & pathogenesis. Secondary (metastatic) liver tumors. Microscopic & gross pathomorphology; differences in diagnosis.
The main primary hepatic carcinoma is hepatocellular carcinoma. Let’s take a look.
Hepatocellular carcinomas are preceded by cellular changes and nodular lesions found in chronic viral hepatitis, alcoholic liver disease and metabolic disease. It is often said that cirrhosis itself is premalignant, however it takes years for this to become HCC. There are two forms of cellular dysplasia, Large cell change and small cell change, these combined with dysplastic nodules mark the major pathways for hepatocellular carcinomas.
HCCs are not uncommon, especially in regions with high Hep B incidence. There are several factors relevant to its pathogenesis
- Major etiologic association with Hep B, C, alcoholic cirrhosis and toxin exposures
- In most cases HCC develops from small-cell high grade dysplastic nodules in cirrhotic livers
- Tumours may arise from mature hepatocytes and progenitor cells
- A universal feature of HCC is the presence of structural and numerical chromosomal abnormalities with genetic instability.
HCCs may appear unifocal, multifocal or diffusely infiltrative, it has a strong propensity for vascular invasion, increasing the risk of metastases. On histological examination, HCCs can show well differentiated lesions that produce hepatocytes arranged in regular patterns or very poorly differentiated cell structure.
Gross: hepatocellular carcinoma – a large, multinodular, yellow-tan tumour bulging from the cut surface, with smaller satellite nodules beside it (left) – HCC is often multifocal.
Image: “Hepatocellular carcinoma 1” by unknown author, Public domain, via Wikimedia Commons.
Remember: telling the two primary carcinomas apart –
- HCC: trabecles and sheets of hepatocyte-like cells, sometimes producing bile; serum alpha-fetoprotein often raised; grows into portal and hepatic veins
- Cholangiocarcinoma: gland-forming, mucin-producing adenocarcinoma in dense desmoplastic stroma; AFP not raised; risk factors are primary sclerosing cholangitis and liver flukes (Opisthorchis, Clonorchis)
Secondary tumours
- Most common are metastatic carcinomas from the colon, lung and breast
- Metastatic cancers are more common than primary cancers
- Normal methods of metastasis