Hepatosplenic T-cell lymphoma (HSTCL) is a type of cancer that affects cells of the immune system called T lymphocytes, or T cells. T cells are a type of white blood cell that helps the body fight infection. HSTCL is an extremely rare disease. It is most commonly diagnosed in younger adults, and it is more common in men.
Lymphoma is grouped into two broad categories: Hodgkin lymphoma and non-Hodgkin lymphoma. HSTCL is a type of non-Hodgkin lymphoma. More specifically, it falls into a subtype of non-Hodgkin lymphoma called peripheral T-cell lymphoma. In this subtype, lymphoma forms in lymphoid tissues outside of the bone marrow. HSTCL primarily affects the liver and the spleen. HSTCL makes up less than 5 percent of peripheral T-cell lymphomas.
T cells support the immune system by recognizing foreign molecules, or antigens. T cells can directly interact with these antigens through molecules called T-cell receptors. One kind of T-cell receptor is called the gamma-delta T-cell receptor. Cells that have this receptor are known as gamma-delta T cells. Gamma-delta T cells make up a small percentage of all T cells in the body. Genetic abnormalities can cause gamma-delta T cells to multiply out of control, leading to cancer. HSTCL develops from gamma-delta T cells. It can also be called hepatosplenic gamma-delta T-cell lymphoma.
Although the exact cause of HSTCL remains unknown, it is more commonly found in people who have chronic problems with their immune systems. About 20 percent of HSTCL cases occur in people with long-term immunosuppression or dysregulation. Additionally, people treated as children for inflammatory bowel disease may be at an increased risk for developing HSTCL.
HSTCL often causes symptoms common to many other forms of lymphoma called B symptoms. These include:
Other symptoms of HSTCL can include:
Unlike many other forms of non-Hodgkin lymphoma, HSTCL generally does not cause swollen lymph nodes (lymphadenopathy).
To diagnose HSTCL, doctors perform a series of tests.
A blood test is performed to measure the complete blood cell count. HSTCL generally causes low levels of mature blood cells, including red blood cells, white blood cells, and platelets.
Cancerous T cells can often be found in the bone marrow (spongy tissue in the middle of some bones) of people with HSTCL. Doctors check for cancerous cells in the bone marrow using tests such as a bone marrow biopsy and bone marrow aspiration. A bone marrow biopsy involves taking a small tissue sample from the bone marrow for testing. In a bone marrow aspiration, a doctor uses a thin needle to remove liquid from the bone marrow. Both tests allow doctors to examine the bone marrow for the presence of cancer cells.
Collecting and examining a tissue sample from the liver is also important in diagnosing HSTCL. A pathologist can analyze the tissue sample under a microscope and look for cancer cells in the liver.
For some people, a technique called flow cytometry may be used to help diagnose HSTCL. Flow cytometry can identify a specific kind of cell in a blood sample with many different cell types. It can be used to look for markers of cancer cells and find evidence of HSTCL in a blood sample.
CT scans and positron emission tomography combined with CT (PET-CT) scans are used to image the tissues within the body. These tests can look for enlargement of the spleen and liver — an important observation for the diagnosis of HSTCL.
Because it is so rare, there is no specific therapy or treatment regimen to treat HSTCL. A person diagnosed with HSTCL may be given lymphoma treatment options like chemotherapy or a stem cell transplant.
Chemotherapy is one common option to treat HSTCL. Chemotherapy kills cells that multiply quickly, including cancer cells. There are many different chemotherapeutic drugs, and they are often given in certain combinations. Some common chemotherapy drug combinations used to treat HSTCL include:
Also called a bone marrow transplant, a stem cell transplant involves replacing the cells of the bone marrow with healthy cells. This procedure allows a person undergoing treatment to tolerate higher doses of chemotherapy. A stem cell transplant can be allogeneic (stem cells come from a donor) or autologous (stem cells come from the person’s own body). A stem cell transplant may be recommended to people in good health who have responded to chemotherapy.
Due to the lack of effective targeted treatments, people diagnosed with HSTCL may be encouraged to participate in clinical trials. A clinical trial allows a person to potentially benefit from new therapies that are still being studied. Although clinical trials specific for HSTCL are not very common, people may be eligible to participate in other studies — particularly if their cancer has not responded to other treatments, or if it initially responded to treatment but eventually came back (relapsed).
HSTCL has a poor prognosis (outlook). Its five-year survival rate is less than 15 percent. Allogeneic (donor) stem cell transplants are associated with improved prognosis.
HSTCL is a challenging disease to study because there are so few cases. Greater participation in clinical trials may improve our understanding of this type of cancer and open the door for more effective treatments.
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