Accessory Spleen - Structure, Formation, Diagnosis, and Treatment

Creator: Dr. Ruchika Singh
Published: 2022-11-11T14:33:30

3 min read

0

Share

Verified data

0

3 min read

Share

The accessory spleen is a developmental defect that leads to the formation of an extra spleen. The article explains the anomaly in detail.

Written by

Dr. Ruchika Singh

Medically reviewed by

Dr. Kaushal Bhavsar

November 11, 2022

February 6, 2023

Contents

Share

Contents

How Is the Structure of Accessory Spleen?
How Is the Accessory Spleen Formed?
Where Are Accessory Spleen Found?
Does an Accessory Spleen Cause Pain?
How to Make Diagnosis of Accessory Spleen?
What Is the Treatment for Accessory Spleen?
Can an Accessory Spleen Grow?

Introduction:

An accessory spleen is also called a supernumerary spleen, a splenunculus, or a splenule. It is a benign and asymptomatic condition in which the splenic tissue is seen outside the normal spleen. Almost 10% to 30% of the population have an accessory spleen. The splenic bud can be between one and six in number with varying sizes. Commonly the accessory spleens are formed due to developmental anomalies and are often misunderstood as splenosis, a form of ectopic splenic tissue.

Splenosis is formed due to trauma which causes a portion of the spleen to break off and embed itself somewhere in the peritoneal cavity. An accessory spleen is similar to splenosis functionally and historically; however, it can be differentiated because splenosis lacks features such as smooth muscle elements, a thick capsule, and blood supply from the splenic artery. The accessory spleen possesses these characteristics.

How Is the Structure of Accessory Spleen?

An accessory spleen is physiologically and morphologically similar to a normal spleen, thus composed of a similar structure and carrying out the same functions. A spleen is a versatile organ that is responsible for several functions, such as generating immunity and filtering blood. Each function is carried out by specific tissues present in the spleen, known as red pulp and white pulp.

The red pulp is formed from connective tissue, which helps to form sinuses and cords containing white blood cells. These sinuses create empty passages which allow the blood to flow and get exposed to white blood cells. This filtration is essential to remove old and damaged red blood cells and destroy any foreign microbe present such as bacteria, viruses, or fungi. The white pulp is more complex in the division. It is responsible for the production and maturation of white blood cells. It has three areas, including the periarteriolar lymphoid sheaths, marginal zone, and lymph follicles.

The periarteriolar lymphoid sheaths are filled with T- lymphocytes and surround the blood supply by arteries.
The lymph follicles are filled with B- lymphocytes and located between the periarteriolar lymphoid sheaths and marginal zone.
The marginal zone is filled with antigen-presenting cells.

How Is the Accessory Spleen Formed?

The accessory spleen is formed due to the partial fusion of mesenchymal buds at the time of development. Accessory spleen tissue can arise from the midline of the path the spleen takes during development.

Where Are Accessory Spleen Found?

The accessory spleen can be formed in several locations; some of them are:

Almost 75% of all accessory spleens are found in the splenic ilium. It is the site of the entrance of blood vessels into the spleen.
Another location where almost 20% of all accessory spleen are found is near the tail of the pancreas.
The rest, 50% of the accessory spleen, can be found in the ligaments, the stomach wall, the intestine, the mesentery, the greater omentum, the gastrosplenic ligaments, or even the scrotum or pelvis.

Does an Accessory Spleen Cause Pain?

It is rarely noticed that the accessory spleen causes pain. It can be due to torsion of the spleen, which leads to hemorrhage, spontaneous rupture, or cyst formation.

What Is Torsion of Accessory Spleen?

It is a very rare cause of abdominal pain but one of the causes of ischemia of the spleen. It causes hemorrhages, rupture of spleen tissue, and necrosis.

What Conditions Lead to Removal of Accessory Spleen?

The most preferred situation for surgical removal of an accessory spleen without removing the normal spleen is torsion of an accessory spleen. Symptoms of torsion include flank pain and nausea. Pain arising from the torsion could be due to infarction or strangulation, direct interference with adjacent organs, or venous congestion due to twisting of the vascular pedicle. Consequences such as peritonitis, hemorrhagic shock, and bowel obstruction can occur due to untreated torsion of an accessory spleen.

How to Make Diagnosis of Accessory Spleen?

Ultrasound and computed tomography are useful aids for diagnosing the presence of an accessory spleen. Torsion of an accessory spleen will appear as an hypoenhancing mass in computed tomography and an iso-echoic or hypoechoic mass on ultrasound. However, it is very difficult to diagnose the accessory spleen pre-operatively.

What Is the Treatment for Accessory Spleen?

The treatment option for the accessory spleen is splenectomy, which includes the removal of the entire spleen along with the accessory spleen. As the diagnosis is complex, it is always suggested to remove the entire spleen to avoid complications.

Can an Accessory Spleen Grow?

A normal spleen cannot regenerate once removed from the body, but an accessory spleen can grow and function without the main spleen.

Conclusion:

Accessory spleens are developmental anomalies formed at the time of development from the main spleen cells. The structure and function of accessory spleens are similar to that of the main spleen. Accessory spleens can be developed in several parts of the body, such as the tail of the pancreas, the wall of the stomach, the wall of the intestine, gastrosplenic ligaments, or even the scrotum and pelvis region. The treatment for the accessory spleen is suggested only in cases of torsion, as there can be serious issues such as spleen ischemia, hemorrhage, and necrosis.

Frequently Asked Questions

1. What Is the Accessory Spleen’s Most Frequent Location?

The primary location where accessory spleens are most commonly found is in proximity to the spleen's hilum. However, they can also occur at various other sites within the abdominal and pelvic regions

2. Is Spleen an Accessory Organ?

It is important to note that the spleen itself is not considered an accessory organ. The spleen is a vital organ situated in the upper left quadrant of the abdomen, serving essential functions in immune response, blood filtration, and platelet storage.

3. What Does an Accessory Spleen Appear Like in Ultrasound Imaging (USG)?

In ultrasound (USG) imaging, additional spleen is a term used to describe a small, distinct piece of spleen tissue that exists independently of the main spleen. This tissue can manifest as a small, round, or oval mass, occasionally leading to the misidentification of other abdominal masses if not correctly identified.

4. How Does an Ectopic Spleen Differ From an Accessory Spleen?

While "ectopic spleen" and "accessory spleen" are often used interchangeably, there is a subtle distinction between the two terms. An accessory spleen typically refers to a small, supplementary piece of spleen tissue that is usually located near the primary spleen or along the path of splenic vessels. Conversely, an ectopic spleen denotes spleen tissue situated in a location beyond its typical anatomical position, such as within the abdomen or pelvis.

5. What Is the Medical Term for an Accessory Spleen?

One word for an accessory spleen in medicine is "splenunculus" or "splenule." A small additional spleen that can form in addition to the primary spleen is known as an accessory spleen. It can be found in the abdomen in a number of places, including the spleen, the splenic ligaments, and other areas of the abdominal cavity. It contains normal splenic tissue.

6. What Factors Contribute to the Development of an Accessory Spleen?

The precise etiology of an accessory spleen is not always clear. It is generally believed to develop during embryonic spleen formation, where multiple small clusters of splenic tissue can originate and remain separate from the main spleen. These clusters can give rise to accessory spleens at various sites within the abdomen and pelvis. Accessory spleens are typically benign and typically do not necessitate treatment unless they cause symptoms or are misidentified as other medical conditions.

7. List the Seven Organs Considered as Accessory Organs.

The term "accessory organs" commonly refers to organs that are not part of the primary digestive system but have roles in digestion and other bodily functions. These auxiliary organs encompass:
- Liver
- Gallbladder
- Pancreas
- Salivary glands (parotid, submandibular, and sublingual glands)
- Appendix
- Adrenal glands
- Spleen (though it is important to note that the spleen itself is typically not classified as an accessory organ).

8. What Is the Typical Size Range of Accessory Spleens?

The size of accessory spleens can exhibit considerable variation. Typically, they are small, with diameters ranging from a few millimeters to several centimeters. However, in certain instances, accessory spleens can grow larger, reaching dimensions of several centimeters. The size of an accessory spleen is influenced by factors like genetics and individual variability.

9. Do Accessory Spleens Pose Any Harm to Health?

Generally, accessory spleens are not considered harmful. They are benign structures that usually do not pose health concerns. In fact, most individuals with accessory spleens remain unaware of their existence since they rarely produce symptoms or health issues. Nonetheless, in exceptional cases, if accessory spleens undergo significant enlargement or are mistaken for other abdominal masses, they may potentially cause symptoms such as abdominal discomfort or pain. In such instances, medical assessment and, on rare occasions, surgical intervention may be considered.

10. Is It Possible for an Accessory Spleen to Increase in Size?

Yes, it is possible for an accessory spleen to increase in size, although it usually remains relatively small. The size of an accessory spleen can differ from person to person and may change over time, influenced by various factors including genetics and individual characteristics.

11. What Potential Indicators May Suggest the Presence of an Accessory Spleen?

Most individuals with accessory spleens do not encounter any symptoms or health complications related to these structures. Accessory spleens are generally harmless and do not give rise to health issues. However, in exceptional instances, if an accessory spleen enlarges significantly or is mistaken for another abdominal mass, it has the potential to cause symptoms or health problems.
- Abdominal pain or discomfort.
- The sensation of fullness or bloating.
- Detectable mass or lump.
- An enlarged accessory spleen can lead to rare complications like tissue death (infarction) or rupture, resulting in severe abdominal pain and necessitating medical attention

12. Does an Accessory Spleen Have Any Advantageous Functions?

Generally, accessory spleens are not considered "beneficial" in the sense of having a distinct physiological function akin to the primary spleen. Instead, they are remnants of embryonic development and are typically noncancerous. While they do not serve a known purpose, they also do not pose harm in most cases. If an accessory spleen becomes symptomatic or causes discomfort, medical assessment may be required to determine the appropriate course of action, which may involve monitoring, medication, or, in rare situations, surgical removal.

13. Can a Splenule, or Accessory Spleen, Generate Discomfort?

Yes, a splenule, also known as an accessory spleen, has the potential to cause discomfort or pain if it enlarges or applies pressure to nearby organs or tissues. While most accessory spleens are typically small and do not cause any pain or inconvenience, significant growth or a particular position may result in abdominal pain or discomfort.

14. Is It Possible to Lead a Healthy Life Without a Spleen?

Living without a spleen is feasible, but it's important to recognize that the spleen plays a vital role in the immune system and blood filtration. When circumstances necessitate spleen removal, whether due to injury, illness, or other medical reasons (known as splenectomy), individuals can lead relatively normal lives. However, they do face an elevated risk of certain infections, particularly those caused by encapsulated bacteria. To manage this risk, healthcare providers often recommend vaccinations against these bacteria before or after splenectomy and may prescribe preventive antibiotics in certain situations. Maintaining good hygiene and promptly seeking medical attention for signs of infection is crucial for those without a spleen.

15. Is There a Risk of Rupture Associated With Accessory Spleens?

Yes, although it is uncommon, an accessory spleen can potentially rupture. This may happen if the accessory spleen undergoes significant enlargement or sustains trauma. Rupture of an accessory spleen can result in internal bleeding and abdominal pain. If an individual with an accessory spleen experiences sudden and severe abdominal pain, it is imperative to seek immediate medical attention, as this could indicate rupture or other complications. While most accessory spleens remain asymptomatic and don't rupture, it is essential to be aware of the rare possibility of such occurrences.

Sources

Dr. Kaushal Bhavsar

Pulmonology (Asthma Doctors)

Rate this article

Tags:

accessory spleen

Do you have a question on

accessory spleen

Ask a doctor online

*guaranteed answer within 4 hours

Disclaimer: No content published on this website is intended to be a substitute for professional medical diagnosis, advice or treatment by a trained physician. Seek advice from your physician or other qualified healthcare providers with questions you may have regarding your symptoms and medical condition for a complete medical diagnosis. Do not delay or disregard seeking professional medical advice because of something you have read on this website. Read our Editorial Process to know how we create content for health articles and queries.