Lymphoma: Types, Symptoms, Causes, Risks, Diagnosis, Treatment and Outlook

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Lymphoma cancer cell

 

1Overview

Lymphomas are composed of groups of malignant diseases that originate from B-cells and T-cells in the lymphatic system. There are two traditional groups of lymphomas: Hodgkin and non-Hodgkin lymphoma. However, it is now known that Hodgkin lymphoma is only one of the many subtypes of lymphomas. Similarly, non-Hodgkin lymphoma is a relatively meaningless term because it represents all the remaining subtypes of the disease. Non-Hodgkin lymphoma is less predictable compared to Hodgkin lymphoma. The prognosis of this disease depends on the stage, treatment, and the histologic type. The clearest risk factor for the disease is suppression of the immune system, which is usually associated with HIV/AIDS, or medication used to prevent organ rejection in transplant cases. Hodgkin lymphoma is histopathologically characterized by the presence of the Reed-Sternberg cells. This type of lymphoma is rare, but it is one of the best-characterized malignancies of the lymphatic system 

2Types

Although the classical separation of lymphomas into Hodgkin and non-Hodgkin lymphomas is no longer scientifically accurate, it is still a useful guide when understanding the disease.

Non-Hodgkin lymphoma develops in the lymphatic system when lymphocytes become damaged and mutate. They grow abnormally and they also multiply at a rapid rate. This causes the lymph nodes to enlarge and tumors to appear. These damaged lymphocytes begin to replace the body’s normal lymphocytes and the person becomes susceptible to infections. Non-Hodgkin lymphoma can occur in one lymph node only, in a group, or in organs, such as the liver.

There are two main types of Non-Hodgkin lymphoma based on the type of cell where cancer started. Therefore, non-Hodgkin lymphoma may either be the B-cell or T-cell variety. B-cell lymphomas may be one of the following: diffuse large B-cell, follicular, small lymphatic, or mantle cell. T-cell lymphomas may be precursor T-lymphoblastic, peripheral T-cell, or cutaneous T-cell.

On the other hand, Hodgkin lymphoma can be classified into two types: classical Hodgkin lymphoma and nodular lymphocyte-predominant Hodgkin lymphoma. Four main subtypes of classical Hodgkin lymphoma have been identified: nodular sclerosis, mixed cellularity, lymphocyte-depleted, and lymphocyte-rich classical. The nodular lymphocyte-predominant Hodgkin lymphoma is a subtype of Hodgkin lymphoma that occurs in about 5% of patients. 

3Symptoms

There are no symptoms specific to lymphomas. In fact, many of the signs and symptoms that are associated with the disease are fairly common, such as fatigue, fever, coughing, and night sweats. Patients often see their doctor because they believe they have the long-standing flu or respiratory infection.

The majority of people diagnosed with Hodgkin and non-Hodgkin lymphoma have no symptoms. However, the most common warning sign of the disease is lymph node swelling. This may or may not be painful and most often occurs in the neck. Some people may also experience swelling in other parts of the body, such as the groin and armpits, where lymph nodes are also located. Other signs may include unexplained weight loss, intermittent fevers, sweating, and/or lack of energy. A less common symptom is persistent itching that becomes more severe over time. It usually presents over the arms, trunk, and legs. Shortness of breath, coughing, or chest discomfort may be signs of cancer in the chest. In the early stages of the disease, no pain is usually involved. 

4Causes

Lymphomas arise because the genes within a lymphocyte (a white blood cell) have mutated. These changes make the cell grow and alters the way that it divides. They may also prevent the cells from dying when it normally should. While there are many known risk factors for developing lymphomas, the exact causes or mechanisms by which people develop the disease are unknown.

B-cell non-Hodgkin lymphomas are characterized by specific mutations in genes. These are translocations, which juxtapose several.

with one of the immunoglobulin loci. Other researchers have found that mutations in the tumor suppressor genes CD95 and ATM can cause Hodgkin and non-Hodgkin lymphomas.

Infections are also thought to contribute to the pathogenesis of lymphomas. In particular, the Epstein-Barr virus is found in B cells and, in rare cases, it is involved in the development of malignancies.

5Risk Factors

There are various risk factors for developing lymphomas. Some people, such as those with HIV, are at an increased risk because of their weakened immune system. Drugs used to treat immune system disorders may put the person at risk for developing lymphomas. These drugs are commonly given to reduce the risk of organ rejection after transplant and are called immunosuppressive agents. In this situation, post-transplant lymphoproliferative disorders (PTLDs) develop.

An overactive immune system may also put people at risk for lymphomas. This happens in cases of autoimmune disorders. For instance, having Sjogren’s syndrome increases the risk of developing a lymphoma. Another example is that having Hashimoto’s thyroiditis can increase the risk of developing lymphomas as well.

Infection can directly or indirectly cause lymphomas. The Epstein-Barr virus is a virus that causes glandular fever and is associated with several types of lymphomas. The majority of people in the world are infected with the virus but are asymptomatic. The virus is found in some Hodgkin lymphomas. Hepatitis C virus has also been found in people with diffuse large B-cell lymphoma.

Previous cancer treatments can increase the risk of developing lymphomas. This is thought to be due to the effects of chemotherapy on the genes of the lymphocytes.

Older age is a risk factor for developing lymphomas. These diseases tend to be more common in older people. As a person ages, more changes occur in the cells and genes have a tendency to mutate, possibly leading to cancer.

6Diagnosis

An accurate assessment of a patient suspected of having a lymphoma requires a number of diagnostic tests. For Hodgkin lymphoma, pathologists will conduct a biopsy in order to check for the presence of Reed-Sternberg cells in the surrounding tissue. They will confirm the diagnosis by analyzing the markers that are present on the surface of the cells. In the classical Hodgkin lymphoma variant, the antigens that are indicative of a diagnosis are CD15 positive and CD30 positive. In nodular lymphocytic predominant Hodgkin lymphoma, the diagnostic proteins are CD20 positive, CD15 negative, and CD30 negative.

Blood tests are also required for a diagnosis. These tests are conducted to determine the morphology, or physical appearance, of other cells in the blood. Bone marrow extraction may also be performed to check whether the lymphoma has spread to the bones.

Imaging tests can also be performed in order to check for metastasis. A CT scan may be ordered to check whether the lymphoma or cancer has spread to the pelvis, chest, or abdomen. A PET scan can also be requested in conjunction with a CT scan. Aside from these, an ultrasound can be requested to check whether there are swollen lymph nodes or lumps in other parts of the body, such as in internal organs.

7Treatment

The treatment of lymphomas depends on the extent of disease, the histologic subtype, and the patient’s age. However, the most common type of treatment for Hodgkin lymphoma is “involved field” radiation therapy with chemotherapy. This type of therapy targets the Hodgkin lymphoma cells. Then, chemotherapy is used to eradicate the neighboring cells.

Chemotherapy alone may be given without radiation therapy to patients whose diseases are widespread, who have a fever, night sweats, and weight loss. This treatment modality usually involves four drugs in combination. These drugs are usually dissolved in fluids and administered through an IV line.

8Outlook

The prognosis for patients depends on the stage of the disease. In general, more advanced stages of the disease leads to reduced chances of survival.

The treatment itself affects the person’s prognosis. Patients who have treated 20 years ago through aggressive radiation therapy are at increased risk of developing second cancer. These second cancers are usually of the stomach, lung, heart, or soft tissues.

Women or girls under the age of 30 who were treated with radiation for breast cancer are at an increased risk of developing breast cancer 15-20 years later. In addition, girls who are treated for lymphomas may have trouble becoming pregnant or getting their menstruation. Males who survive cancer are at risk for developing cancer again.

Radiation therapy can cause lung injury and chest radiation places patients at risk for developing lung cancer. It is also risked to heart disease and injury to the thyroid gland, causing hypothyroidism.

Mental health is another concern for patients who have survived cancer treatment. The ordeal often takes years or months out of their lives and this causes significant stress on them and their families. Depression and anxiety are common for those who have undergone chemotherapy.

Nutritional status is another concern, as those who have lost a large amount of weight need to regain it. Unexplained weight loss in patients with cancer is problematic as it contributes to the weakening of the immune system. This is undesirable for those who have undergone treatment for cancer. In addition, there are many other things that affect prognoses, such as coping mechanisms and family support.