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Cancer Classification by histological types:

 

Cancers are categorized in two ways: by the type of tissue where the cancer originates (histological type), and by the primary site or location in the body where the cancer first grew. This section presents you with the first method: classification of cancer based on a histological form.

 

There are hundreds of different cancers from a histological perspective, which are divided into six major categories:

 

  • Carcinoma
  • Sarcoma
  • Myeloma
  • Leukaemia
  • Lymphoma
  • Mixed Types

Carcinoma


Carcinoma refers to a malignant epithelial neoplasm or cancer of the body’s inner or outer lining. Carcinomas, epithelial tissue malignancies, account for 80 to 90 per cent of all cancer cases.


Epithelial tissue can be found all over the body. It is found in the skin, as well as organs and internal passageways, such as the gastrointestinal tract, covering and padding.


Carcinomas are classified into two primary subtypes: adenocarcinoma that occurs in an organ or gland, and squamous cell carcinoma that originates from the squamous epithelium.


Adenocarcinomas usually occur in mucus membranes and are often seen as a thickened white plaque-like mucosa. Sometimes they quickly spread across the soft tissue where they occur. In many parts of the body, squamous cell carcinomas occur.


Most carcinomas involve organs or glands that can secrete, such as breasts that produce milk, or lungs that secrete mucus, or colon or prostate or bladder.

 

Sarcoma


Sarcoma refers to cancer that has its origin in supporting and connective tissues such as bones, tendons, cartilage, muscle, and fat. The most common sarcoma commonly found in young adults frequently presents as a painful mass on the bone. Tumours of sarcoma typically mimic the tissue they develop in.


Examples of sarcomas are:

 

  • Osteosarcoma or osteogenic sarcoma (bone)
  • Chondrosarcoma (cartilage)
  • Leiomyosarcoma (smooth muscle)
  • Rhabdomyosarcoma (skeletal muscle)
  • Mesothelial sarcoma or mesothelioma (membranous lining of body cavities)
  • Fibrosarcoma (fibrous tissue)
  • Angiosarcoma or hemangioendothelioma (blood vessels)
  • Liposarcoma (adipose tissue)
  • Glioma or astrocytoma (neurogenic connective tissue found in the brain)
  • Myxosarcoma (primitive embryonic connective tissue)
  • Mesenchymous or mixed mesodermal tumour (mixed connective tissue types)

 

Myeloma


Multiple myeloma is a cancer that develops in a type of plasma cell called a white blood cell. Plasma cells help you combat diseases by developing germ detecting and destroying antibodies. Multiple myeloma allows the cancer cells to build up in the bone marrow, where healthy blood cells are squeezed out. Instead of generating useful antibodies, the cancer cells produce abnormal proteins which can cause complications. Multiple myeloma care is not necessarily appropriate for people who have no signs or symptoms. There are a variety of therapies available for people with multiple myeloma that need medication to help manage the disease.

 

Leukaemia


Leukaemias are cancers of the bone marrow (the site of blood cell production). Often the disorder is associated with overproduction of white blood cells that are immature. Such young white blood cells are not doing as well as they should be. Therefore the patient is often prone to infection. Leukaemia also affects red blood cells and can cause poor blood clotting and fatigue due to anaemia. 


Examples of leukaemia include:

 

  • Myelogenous or granulocytic leukaemia (malignancy of the myeloid and granulocytic white blood cell series)
  • Lymphatic, lymphocytic, or lymphoblastic leukaemia (malignancy of the lymphoid and lymphocytic blood cell series)
  • Polycythemia vera or erythremia (malignancy of various blood cell products, but with red cells predominating)

 

Lymphoma


Lymphomas form in the glands or nodes of the lymphatic system. The lymphatic system is a network of vessels, nodes, and organs (specifically the spleen, tonsils, and thymus) that purify bodily fluids and produce infection-fighting white blood cells, or lymphocytes. Unlike the leukaemias which are sometimes called “liquid cancers,” lymphomas are “solid cancers.” Lymphomas may also occur in different organs such as the stomach, breast or brain. These lymphomas are called extranodal lymphomas. The lymphoma is subclassified into two categories: lymphoma of Hodgkin and lymphoma of Non-Hodgkin. The presence of Reed-Sternberg cells diagnostically differentiates Hodgkin lymphoma from Non-Hodgkin lymphoma.

 

Mixed Types


The type components may be within one category or from different categories. Some examples are:

 

  • adenosquamous carcinoma
  • mixed mesodermal tumour
  • carcinosarcoma
  • teratocarcinoma