What is the Marginal Zone?

The marginal zone is an area located in the spleen. Generally, it is surrounded by the organ’s red pulp and white pulp, which are needed components in body immunity. In humans, the area does not fully develop until after an individual reaches two years of age. Abnormal growth in this area can give rise to a cancerous condition called marginal zone B-cell lymphoma.

At the highest level, marginal zones are part of the lymphatic system. This body system contains the spleen, the thymus gland, and various vessels and lymph nodes located throughout the body. These body parts help generate and transport immunity-essential creations like lymph, a liquid substance important in combating harmful substances that enter the body. Marginal zones are specifically found in the spleen.

Nearly every animal has a spleen, and a human spleen resides in the upper abdomen. The organ is vital to humans for its removal capacities. Spleens can eliminate unneeded red blood cells from the body and they can also provide immunity against invasive substances. The former function is the responsibility of the blood-cell containing nonlymphoid red pulp, whereas lymphatic immunity functions take place in the lymphoid white pulp.

Marginal zones play an important role in the spleen’s immune responses. The area is composed of cells that trap disease-causing substances entering the body such as bacteria. Cells called lymphocytes found in the spleen then eradicate the substances in a process known as humoral immunity.

Cells in the marginal zone are also known as B-cells because they derive from bone marrow and they do not circulate but remain in the spleen. B-cells work by creating proteins called antibodies that can bind to, identify, and subsequently break down the invasive substances. Some of these antibodies can be used as markers to identify and classify marginal zone cells.

Lymphomas can sometimes occur in the marginal zone. A lymphoma is the result of a cancerous growth in the lymphatic system. Mutations of immune cells can cause abnormal cell division or protein production, thereby creating the tumor masses. These mutations may result from body infections.

Subtypes of lymphomas may exist within a marginal zone cancer. Namely, nodal marginal zone lymphomas impact only the lymphatic system, while extranodal lymphomas can spread outside of the lymphatic system to the digestive tract or other areas. In either case, marginal zone lymphomas constitute less than five percent of lymphoma cases. Radiology or chemotherapy treatments will likely be needed for advanced conditions.