Angioimmunoblastic T-cell Lymphoma (AITL) is a rare, fast-growing non-Hodgkin lymphoma originating from T-cells, a component of the immune system. This cancer involves the abnormal growth of these T-cells and primarily affects adults, with an average diagnosis age of 65 to 70. A distinct feature of AITL is the significant and irregular reaction it triggers throughout the immune system.
What is Angioimmunoblastic T-cell Lymphoma?
The name Angioimmunoblastic T-cell Lymphoma offers clues to its nature: “angio” relates to blood vessels, “immuno” to the immune system, and “blastic” to immature cells. AITL is a subtype of Peripheral T-cell Lymphoma (PTCL), a group of cancers developing from mature T-cells outside the bone marrow. Healthy T-cells destroy pathogens like viruses and bacteria.
In AITL, a specific type of T-cell, the follicular helper T-cell, becomes cancerous and proliferates. These cells gather in lymph nodes, bone marrow, and can impact organs like the liver and spleen. The disease is not solely defined by these cancerous T-cells; it also involves a significant reaction from other non-cancerous immune cells, including B-cells. This reaction contributes to many symptoms.
This systemic immune response is a defining characteristic of AITL. The Epstein-Barr virus (EBV) is detected in the B-cells within affected lymph nodes in a high percentage of cases. However, EBV is not believed to be the direct cause of the T-cell cancer. This interaction between cancerous T-cells and a highly activated immune system makes AITL a complex disease.
Recognizing the Symptoms
The initial signs of AITL are often generalized and shared with other lymphomas. These “B symptoms” include unexplained fevers, drenching night sweats, and significant unintentional weight loss. These symptoms often prompt medical investigation and can signal an advanced disease stage.
More specific symptoms include widespread, painless swelling of lymph nodes in the neck, armpits, or groin. Many individuals also develop an itchy skin rash, which can be flat or raised. An enlarged liver and spleen (hepatosplenomegaly) is another common finding, causing fullness or discomfort in the abdomen.
A distinguishing feature of AITL is the development of autoimmune-like conditions, as the immune system attacks healthy tissue. This can lead to autoimmune hemolytic anemia (destruction of red blood cells) and immune thrombocytopenia (destruction of platelets). Joint pain and swelling are also reported, reflecting the systemic immune disturbance.
The Diagnostic Process
A lymph node biopsy is the most definitive step in diagnosing AITL. An excisional biopsy, where an entire lymph node is removed, is preferred over a needle biopsy to provide a sufficient tissue sample. A pathologist analyzes the tissue for the disappearance of normal lymph node structure and the presence of abnormal T-cells.
The pathologist also identifies a proliferation of small blood vessels and follicular dendritic cells, which are hallmarks of the disease. Blood tests are also performed to check for anemia, which can result from the autoimmune response. These tests also look for other abnormalities like elevated protein levels in the blood (hypergammaglobulinemia).
Imaging tests are used for staging, which determines the cancer’s spread throughout the body. Positron emission tomography (PET) scans and computed tomography (CT) scans are standard procedures to visualize affected lymph nodes and organs. A bone marrow biopsy is also a routine part of the workup, as AITL often involves the bone marrow. Most individuals are diagnosed at Stage III or IV, meaning the cancer is widespread.
Therapeutic Strategies
Treatment for AITL is initiated soon after diagnosis due to its fast-growing nature. The most common initial therapy is combination chemotherapy, such as CHOP. This regimen includes four drugs and is often administered with a steroid like prednisone.
For patients who relapse or do not respond to initial chemotherapy, other treatments are explored. These second-line therapies may involve different chemotherapy combinations or targeted therapy agents. Targeted drugs are designed to interfere with specific molecules involved in the cancer’s growth and survival.
For eligible patients, a stem cell transplant may be offered to consolidate the response to chemotherapy and provide a longer-lasting remission. An allogeneic stem cell transplant, using healthy stem cells from a matched donor, is often considered. This procedure replaces the patient’s diseased bone marrow with a new immune system from the donor to help fight remaining lymphoma cells.
Prognosis and Disease Course
The course of AITL can be highly variable among individuals. The prognosis depends on factors including the patient’s age, overall health, disease stage, and initial response to treatment. Because of these variables, predicting an exact outcome for any single person is not possible.
Survival rates are statistical averages from large patient groups and cannot predict an individual’s outcome. For AITL, the median survival is reported to be under three years. A prognostic tool, the AITL Score, may be used to categorize patients into risk groups based on factors like age and specific blood protein levels.
The disease has a high rate of relapse, meaning the cancer can return after successful treatment. This requires continuous monitoring by a medical team after therapy is completed. The cause of death is often related to complications from infections, as the disease and its treatments weaken the immune system.