What is the most common abnormality of the spleen?

September 27, 2025 •

4 min read

While many conditions can affect the spleen, the most frequently encountered abnormality is not a disease itself but a physical sign of an underlying health issue: splenomegaly, or enlargement. This can be caused by a wide range of factors, from infections to blood cancers.

Quick Summary

The most common abnormality of the spleen is splenomegaly, which is an enlargement of the organ. Although it is a common finding, it signals an underlying medical condition, which can range from a viral infection to more serious issues like liver disease or certain blood disorders, all of which require a professional diagnosis.

Key Points

Splenomegaly is the most common sign: An enlarged spleen, or splenomegaly, is the most frequently observed abnormality, though it is often a symptom of other conditions rather than a primary disease itself.
Causes are diverse: The root causes of splenomegaly are wide-ranging, including infections (like mononucleosis), liver disease (such as cirrhosis), blood disorders (like hemolytic anemia), and various cancers.
Benign lesions are common: Beyond enlargement, focal lesions like splenic hemangiomas (the most common benign tumor) and cysts (the most common focal benign mass) are frequent incidental findings during imaging.
Accessory spleens are a frequent congenital variant: Many people have a small extra piece of splenic tissue, known as an accessory spleen. It is generally harmless but can be relevant during surgery for hematologic conditions.
Diagnosis requires testing: A proper diagnosis for any splenic abnormality relies on a combination of a physical exam, blood tests, and imaging techniques such as ultrasound, CT, or MRI.
Treatment targets the underlying cause: The management strategy focuses on treating the condition that is causing the splenic issue. A splenectomy is typically reserved for severe complications like rupture or certain resistant blood disorders.

Splenomegaly: The most common splenic abnormality

Although it may be discovered incidentally during a physical examination or imaging, an enlarged spleen is the most common abnormality observed in this organ. Splenomegaly is not a standalone disease but a symptom of many possible underlying conditions that can affect the spleen's size and function. Its presence indicates that the spleen is working harder than usual, often to fight an infection, filter out damaged cells, or respond to an issue with blood flow.

Causes and symptoms of an enlarged spleen

Several different issues can lead to an enlarged spleen, and understanding the root cause is critical for effective treatment. Some of the most common causes include:

Infections: Viral infections, such as infectious mononucleosis (mono), are a frequent cause of temporary splenomegaly, especially in young adults. Other infections can also play a role, including bacterial endocarditis, malaria, and even some parasitic infections.
Liver Disease: Conditions such as cirrhosis can cause an increase in pressure in the portal vein, which can lead to congestive splenomegaly.
Blood Disorders: Various types of hemolytic anemia, where red blood cells are destroyed prematurely, can cause the spleen to enlarge as it overworks to filter out damaged cells. Hereditary spherocytosis is a well-known example of this.
Blood Cancers: Cancers affecting the blood and lymphatic system, like leukemia and lymphoma, can cause the spleen to swell as cancerous cells accumulate within it.
Metabolic Disorders: Rare inherited conditions such as Gaucher disease or Niemann-Pick disease can lead to the buildup of abnormal substances in the spleen, causing it to become enlarged.

Symptoms of splenomegaly, if present at all, can be vague and are often related to the underlying condition. They may include pain or a feeling of fullness in the left upper abdomen, fatigue, easy bleeding, frequent infections, or feeling full after eating only a small amount.

Other common and incidental splenic findings

Beyond general enlargement, several other abnormalities are frequently identified in the spleen, often during imaging for unrelated issues:

Splenic Cysts: Cysts are a common focal lesion, and they can be either non-parasitic or parasitic. The most common are pseudocysts, which lack a true epithelial lining and often develop after a traumatic injury or hemorrhage. Epithelial cysts (true cysts) are less common and congenital.
Splenic Hemangiomas: As the most common benign tumor of the spleen, hemangiomas are vascular lesions that are typically asymptomatic and small in size. In rare cases, very large hemangiomas can rupture, causing internal bleeding.
Accessory Spleen (Splenunculus): A congenital anomaly, an accessory spleen is the presence of one or more small extra splenic tissues, most often found near the hilum of the main spleen. They are a common finding and rarely have clinical significance unless they are removed during a splenectomy for a hematologic disorder, which can cause the disease to recur.

Comparison of benign versus malignant spleen lesions


Feature	Benign Lesions (e.g., Cysts, Hemangiomas)	Malignant Lesions (e.g., Lymphoma, Metastasis)
Incidence	Fairly common; cysts and hemangiomas are frequent incidental findings.	Less common; primary malignancies are rare. Secondary metastasis is infrequent.
Presentation	Often asymptomatic. May cause pain or fullness if very large.	May present with splenomegaly, weight loss, night sweats, fever, and fatigue.
Appearance on Imaging	Typically well-defined, homogeneous. Cysts are fluid-filled; hemangiomas may have a characteristic enhancement pattern.	Can be solitary or multiple lesions, often hypoechoic or hypodense. May have variable enhancement.
Risk of Rupture	Very large hemangiomas or cysts can rupture, but it is rare.	Angiosarcoma, a rare and aggressive malignant tumor, has a high risk of rupture.

The process of diagnosis and management

When a spleen abnormality is suspected, a medical evaluation is required to identify the underlying cause and determine the best course of action. This process typically involves:

Medical History and Physical Exam: The doctor will ask about symptoms, travel history, and other risk factors. A physical exam may involve palpating the abdomen to check for spleen size and tenderness.
Blood Tests: A complete blood count (CBC) can reveal abnormalities in red blood cells, white blood cells, and platelets, which are common with spleen disorders. Liver function tests can also be useful.
Imaging: An abdominal ultrasound is often the first imaging step to confirm splenomegaly and evaluate its size. CT or MRI scans may be used for more detailed characterization of lesions and surrounding organs.
Further Evaluation: In some cases, such as to confirm lymphoma, a bone marrow biopsy may be needed. A needle biopsy of the spleen is rare due to the risk of bleeding. In specific situations, a diagnostic splenectomy may be performed.

Treating splenic abnormalities

Treatment for a splenic abnormality is aimed at addressing the underlying condition. In many cases, such as with minor splenomegaly from mononucleosis, a 'watchful waiting' approach is used, and the spleen returns to normal on its own.

Antibiotics or Other Medications: If a bacterial or parasitic infection is the cause, medication can resolve the issue.
Surgical Removal (Splenectomy): This is considered for severe cases. A splenectomy may be necessary if an enlarged spleen causes serious complications, like a rupture, or for certain blood disorders that do not respond to other therapies.
Radiation Therapy: For some cancers, low-dose radiation may be used to shrink the spleen.

For patients who have had their spleen removed, there is a higher lifelong risk of serious infections. Vaccinations and prophylactic antibiotics may be necessary to manage this risk. Additionally, patients should avoid contact sports and wear a seatbelt to protect their abdomen from trauma. For more information on the various functions of the spleen and related disorders, you can consult sources such as the NIH.

Frequently Asked Questions

An enlarged spleen may cause no symptoms, but it can also lead to pain or fullness in the left upper abdomen, a feeling of fullness after eating little, fatigue, frequent infections, and easy bleeding.

Not always. While it can be a sign of serious conditions like cancer or liver disease, it can also be a temporary response to a viral infection like infectious mononucleosis. A medical evaluation is necessary for an accurate diagnosis.

A splenic hemangioma is the most common benign tumor of the spleen. It is usually small and asymptomatic. While very large ones have a small risk of rupture, most are not dangerous and are simply monitored.

Diagnosis typically involves a physical exam to check for size, blood tests to look for underlying diseases, and imaging studies like an ultrasound, CT, or MRI to visualize the spleen and confirm the abnormality.

Yes, a person can live without a spleen, but it increases the risk for certain serious infections. Vaccinations and antibiotics are often necessary to protect against these infections, especially those caused by encapsulated bacteria.

An accessory spleen is a congenital abnormality where small, additional pieces of splenic tissue exist. These are often discovered incidentally and are usually harmless, though they can sometimes cause disease recurrence if not removed during a splenectomy for a blood disorder.

Splenectomy, the surgical removal of the spleen, is reserved for severe complications, such as a ruptured spleen, massive enlargement causing significant symptoms, or blood disorders that fail to respond to other forms of therapy.