The spleen (from the Greek splen and from the Latin link), is a soft organ of the lymphatic system. It plays a decisive role in immunity and the process of blood cell renewal.

Located under the diaphragm, the spleen is a lymphatic organ that is positioned against the anterior walls of the stomach on the left side of the abdominal cavity. It is a soft organ located in the upper left part of the abdomen. It is found approximately at the level of the 10th and last rib (ribs 11 and 12 being considered as floating ribs), which is called the splenic rib. In normal situation, the spleen is not palpable. It weighs an average of 200 grams, which makes it the largest of the lymphatic organs. The spleen is richly irrigated by blood vessels, on the other hand it does not receive any lymphatic irrigation.

The spleen belongs to the lymphatic system, which includes:

• Lymphatic vessels
• Lymphatic tissue and organs distributed throughout the body. These organs, which contain phagocytes and lymphocytes, are major players in the body’s defense. The spleen therefore plays an essential role from an immune point of view.

Its role is to filter the blood and to purify it. It works mainly to destroy and recycle used red blood cells (iron is used again for example for the production of hemoglobin).

Like the liver, the spleen also acts as a blood reserve for the body.

Before birth, the spleen is the place where white blood cells, red blood cells and blood platelets are made. This is called erythropoiesis.

After birth, the spleen makes only white blood cells.

Splenomegaly : increase in the volume of the spleen. This is the most classic manifestation of the various diseases that can affect this organ. We speak of splenomegaly when the spleen becomes palpable.

Non-Hodgkin lymphoma : the most common cancer of the lymphatic system, it affects around 16 in 100 people. This cancer is formed when lymphocytes, produced in particular in the spleen, proliferate in a disorderly and uncontrolled manner. It occurs most often around the age of 000 and affects an average of 60% of patients infected with HIV.

Hodgkin’s disease : second type of cancer that affects the lymphatic system. It usually develops in the lymph nodes or groin, but can also spread to the spleen.

Spleen cyst : rare pathology generally discovered by chance. They can be congenital or acquired (2). There are several types, including the epidermoid cyst which develops preferentially in young people, with a majority of cases in girls.

Calcification of the walls of the spleen : Generally soft, the walls of this lymphatic organ sometimes calcify. This phenomenon is usually a precursor of the development of a cyst. Numerous pathologies (Bennett’s disease, infantile jaksch-pseudo-leukemic anemia) can cause a significant increase in the volume of the spleen in infants.

Certain drugs such as quinine and adrenaline (4,5) can be responsible for contracting the spleen (or spleno-contraction).

A soft and fragile organ, the spleen can explode in the event of a big shock. In this case, the blood retained in the spleen spills out and can cause hemorrhage. The spleen must then be removed very quickly.

Clinical examination: palpation of the spleen by hand. As its volume increases, the spleen overflows from its area and can therefore be detected by touch.

Ultrasound: medical imaging technique based on the use of ultrasound, inaudible sound waves, which allows to have a global vision (size, shape, wall, vascularization) of the spleen.

Scintigraphy: imaging test that measures the level of degradation of red blood cells by the spleen. It first requires labeling the red blood cells with a radioactive isotope.

Scanner: diagnostic imaging technique which consists of “scanning” a given region of the body in order to create cross-sectional images, thanks to the use of an X-ray beam. The term “scanner” is actually name of the medical device, but it is commonly used to name the exam. We also speak of computed tomography or computed tomography.

Splenectomy: removal of the spleen. It is sometimes necessary, especially in the case of Debler’s anemia. The operation is not trivial since it generally takes several weeks for the body to adapt to this change, time to rebalance the management of the different blood cells.

In Chinese medicine, each of the five fundamental emotions is connected to one or more organs. Worries are for example directly associated with the spleen and pancreas. This idea is conveyed beyond the framework of Chinese medicine. Charles Baudelaire notably devoted a poem to it: Spleen (translation of spleen in English).

In many mammals, the spleen and liver are able to contract in the event of hemorrhage and discharge the blood they store into the general circulation to regulate its volume.