BENIGN TUMOURS (Robbins pp 887)

Liver cell adenomas:

• These are benign neoplasms of hepatocytes. Risk factors include: contraceptives, anabolic & androgenic steroids.
  
• Two important points:
  
• 1) often mistaken for hepatocellular carcinoma,
  
• 2) subcapsular adenomas have tendency to rupture under influence of oestrogen ≫ haemorrhage.
• Morphology: Nodules of tumour tissue are foundm, usually below the capsule. Histologically, you can see nearly normal hepatocytes arranged in a chord structure similar to a normal liver. The lobular structure is not present, the portal areas are missing, and numerous blood vessels are found.

Nodular hyperplasia:

• There are two types in this category: 1) focal nodular hyperplasia, 2) nodular regenerative hyperplasia.
• Morphology: In the former, you will see a stellate central fibrotic scar. From this radiates bands of fibrous tissue to the periphery. This fibrous tissue contains blood vessels and proliferating bile ducts. The parenchyma between these fibrous bands contain normal hepatocytes. In the latter, it affects the whole liver with nodules. These nodules contain hepatocytes surrounded by atrophic cells.

Angiomas (Haemangiomas):

• This is simply increased amounts of blood vessels. These are extremely common in infancy and childhood and they regress spontaneously at or before puberty. The walls of the vessels are the same as those of normal vessels. Haemangiomas can occur in extremeties or entirely within organs (Liver most common).
• Clinical variants: Capillary haemangiomas, cavernous (large dilated vessels) haemangiomas.
• Haemangioendothelioma is a special term applied to tumours that are in between being benign & anaplastic angiosarcomas.
• Similarly, you can get Lymphangiomas. These are exactly the same as haemangiomas except lymph vessels are involved.

Bile duct hamartoma:

• A hamartoma is when an organ has disorganised structures within it, but all structures are present. One example of bile duct hamartomas are: von Meyenburg Complexes: the portal areas usually contain 1 hepatic artery, 1 hepatic vein, 1 bile duct. But in this condition, you get multiple dilated bile ducts right next to the portal areas, THIS IS NOT SUPPOSED TO BE THERE. These “new” bile ducts may communicate with biliary tree, but usually do not contain any bile pigments. It is thought that these “extra” ducts are from failure to involute during embryonic development.

Category: Pathology Notes