Follicular dendritic cell sarcoma (FDC sarcoma) is a very rare type of sarcoma. Some of its symptoms, such as painless swollen lymph nodes , are like that of lymphoma. Lymphoma is a type of blood cancer.

Doctors treat FDC sarcoma as a soft tissue sarcoma. FDC sarcoma develops from specialised cells in the lymph nodes. The lymph nodes are part of the lymphatic system, which helps to fight infection.

Most FDC sarcomas develop in the lymph nodes and are called nodal cancers. But about 30 out of every 100 (30%) develop elsewhere in the body such as:

• head and neck area
• digestive system (bowel, stomach)
• spleen
• liver
• lungs
• skin
• the centre area of the chest and area between the lungs (mediastinum)

These FDC sarcomas are known as extranodal tumours, because they grow outside the lymph nodes.

Causes

We don’t know what causes follicular dendritic cell sarcoma. It’s particularly difficult to find out the cause of a rare cancer because there are so few people with the disease. This makes it hard to find a common link. Doctors have linked follicular dendritic cell sarcoma to Castleman’s disease. This is a condition where non cancerous (benign) tumours develop in the lymph nodes. Researchers have also found that the Epstein Barr virus plays a part in the development of FDC sarcomas of the liver and spleen.

Symptoms

The symptoms of follicular dendritic cell sarcoma vary depending on where in the body it develops. The most common symptom is a painless swelling of a lymph node, usually in the neck. But a swelling can develop elsewhere in the lymphatic system. Follicular dendritic cell sarcomas are described as indolent, which means they grow slowly.  Other symptoms may include:

• a cough
• a sore throat
• difficulty in swallowing
• weight loss
• tiredness
• a painless swelling
• tummy (abdominal pain)
• night sweats
• a high temperature (fever)

Getting diagnosed

You might have a number of tests. These include a:

• CT scan
• PET scan
• chest x-ray
• blood tests

The only way to make a definite diagnosis is to take some cells from the lump (a biopsy) to look at under a microscope. Follicular dendritic cell sarcomas are difficult to diagnose because they can look very like other types of cancer, including lymphomas and other types of sarcoma.

Protein markers

Follicular dendritic cell sarcomas have proteins (markers) on the cells. Specific proteins include CD21, CD23 and CD35. Doctors can test for these proteins to confirm the diagnosis. The testing is called immunohistochemical staining.

Treatment

As follicular dendritic cell sarcoma is very rare, standard treatment guidelines are not that clear compared to most other cancers. Your specialist will discuss this with you. 

Your treatment depends on:

• how big the sarcoma is, and whether it has spread to other parts of the body
• how different the sarcoma cells are from normal cells and how fast they grow (grade) 
• your general health and fitness 

You might have surgery to remove the cancer, followed by chemotherapy or radiotherapy.

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