The spleen, a fist-sized organ located in the upper left side of the abdomen, often goes unnoticed until a health issue arises. This soft, purple organ is nestled behind the stomach and beneath the diaphragm, protected by the rib cage. A common question is whether the spleen can regenerate or “grow back” if removed.
The Spleen’s Vital Roles
The spleen performs several important functions that contribute to overall health. It acts as a filter for the blood, removing old, damaged, or abnormal red blood cells. As blood flows through a maze of narrow passages within the spleen, healthy cells pass through, while unhealthy ones are broken down by specialized white blood cells called macrophages.
Beyond its filtering, the spleen plays a significant part in the body’s immune system. It produces white blood cells, such as lymphocytes, which help fight infections. The spleen also stores a reservoir of red blood cells and platelets, which can be released into circulation if the body experiences significant blood loss.
Spleen Removal
Surgical removal of the spleen, a splenectomy, becomes necessary for various medical reasons. The most common cause is a ruptured spleen, often resulting from abdominal injury, which can lead to life-threatening internal bleeding. Other reasons include certain blood disorders like idiopathic thrombocytopenic purpura (ITP) and hereditary spherocytosis, where the spleen may be overactive in destroying blood cells.
Some cancers, such as certain types of lymphoma and leukemia, or large cysts and tumors, may also necessitate spleen removal. While individuals can live without a spleen, its absence means other organs, like the liver and bone marrow, take over many of its functions. However, living without a spleen increases the risk of certain infections, particularly from encapsulated bacteria, making preventive measures like vaccinations important.
Understanding Splenic Tissue After Removal
The spleen does not typically regenerate itself like some other tissues, such as the liver. However, the body can sometimes develop or retain functional splenic tissue after the main spleen is removed, which might lead to a perception of “regrowth.” This phenomenon can occur in two primary ways: through accessory spleens or via splenosis.
Accessory spleens are congenital pieces of splenic tissue that some individuals are born with. They are found in approximately 10-30% of the population. They are often located near the main spleen or the tail of the pancreas and receive their blood supply from branches of the splenic artery. These accessory spleens are functional and can sometimes enlarge after the main spleen is removed, taking over some of its functions.
Splenosis, on the other hand, is an acquired condition where small implants of splenic tissue scatter throughout the body, most commonly in the abdominal cavity, following a traumatic injury to the spleen or its surgical removal. This occurs when fragments of splenic tissue break off and implant themselves in other locations. Unlike accessory spleens, splenosis is a result of trauma or surgery and involves numerous small nodules. While these implants are composed of viable splenic cells, they do not form a complete, organized organ.
Functional Outcomes of Remaining Splenic Tissue
The presence of accessory spleens or splenosis can provide some degree of splenic function, which may be beneficial for individuals who have undergone a splenectomy. These remnants can help filter blood and contribute to immune responses, potentially reducing the risk of infection compared to a complete absence of splenic tissue. The functional capacity of these tissues is supported by their normal tissue architecture.
Despite their functional contributions, these splenic remnants rarely fully compensate for a missing main spleen. In some cases, accessory spleens can enlarge, or splenosis implants might cause symptoms like abdominal pain. They can also complicate diagnostic imaging. For individuals with blood disorders, the continued presence or enlargement of accessory splenic tissue after splenectomy can sometimes lead to a recurrence of the original symptoms.