Splenomegaly

Definition

The standard system for classifying splenomegaly on radiography is:

• Normal (not splenomegaly): the largest dimension is less than 11 cm
• Moderate splenomegaly: the largest dimension is between 11 and 20 cm
• Severe splenomegaly: the largest dimension is greater than 20 cm Also, a cutoff of a craniocaudal height of 13 cm is also used to define splenomegaly. In addition, individual intervals have been established:

For children, the cutoffs for splenomegaly are given in this table, when measuring the greatest length of the spleen between its dome and its tip, in the coronal plane through its hilum while breathing quietly.

At autopsy, splenomegaly can be defined as a spleen weight above the upper limit of the standard reference range of 230 g.

Splenomegaly refers strictly to spleen enlargement, and is distinct from hypersplenism, which connotes overactive function by a spleen of any size. Splenomegaly and hypersplenism should not be confused. Each may be found separately, or they may coexist. Clinically, if a spleen is palpable (felt via external examination), it means it is enlarged as it has to undergo at least twofold enlargement to become palpable. However, the tip of the spleen may be palpable in a newborn baby up to three months of age.

Signs and symptoms

Symptoms may include abdominal pain, chest pain, chest pain similar to pleuritic pain when stomach, bladder or bowels are full, back pain, early satiety due to splenic encroachment, or the symptoms of anemia due to accompanying cytopenia.

Signs of splenomegaly may include a palpable left upper quadrant abdominal mass or splenic rub. It can be detected on physical examination by using Castell's sign, Traube's space percussion or Nixon's sign, but an ultrasound can be used to confirm diagnosis. In patients where the likelihood of splenomegaly is high, the physical exam is not sufficiently sensitive to detect it; abdominal imaging is indicated in such patients.

In cases of infectious mononucleosis splenomegaly is a common symptom and health care providers may consider using abdominal ultrasonography to get insight into a person's condition., which cites

• However, because spleen size varies greatly, ultrasonography is not a valid technique for assessing spleen enlargement and should not be used in typical circumstances or to make routine decisions about fitness for playing sports.

Causes

The most common causes of splenomegaly in developed countries are infectious mononucleosis, splenic infiltration with cancer cells from a hematological malignancy and portal hypertension (most commonly secondary to liver disease, and sarcoidosis). Splenomegaly may also come from bacterial infections, such as syphilis or an infection of the heart's inner lining (endocarditis). Splenomegaly also occurs in mammals parasitized by Cuterebra fontinella.

The possible causes of moderate splenomegaly (spleen

The causes of massive splenomegaly (spleen 1000 g) are

• chronic myelogenous leukemia
• myelofibrosis
• malaria
• splenic marginal zone lymphoma

Pathophysiology

Splenomegaly can be classified based on its pathophysiologic mechanism:

• Congestive, by pooled blood (e.g., portal hypertension)
• Infiltrative, by invasion by cells foreign to the splenic environment (e.g., metastases, myeloid neoplasms, lipid storage diseases)
• Immune, by an increase in immunologic activity and subsequent hyperplasia (e.g., endocarditis, sarcoidosis, rheumatoid arthritis)
• Neoplastic, when resident immune cells originate a neoplasm (e.g., lymphoma).

Diagnosis

Abdominal CT is the most accurate. The spleen needs to be 2–3 times larger than normal to be palpable below the costal margin in physical examination.

Treatment

If the splenomegaly underlies hypersplenism, a splenectomy is indicated and will correct the hypersplenism. However, the underlying cause of the hypersplenism will most likely remain; consequently, a thorough diagnostic workup is still indicated, as, leukemia, lymphoma and other serious disorders can cause hypersplenism and splenomegaly. After splenectomy, however, patients have an increased risk for infectious diseases.

Patients undergoing splenectomy should be vaccinated against Haemophilus influenzae, Streptococcus pneumoniae, and Meningococcus. They should also receive annual influenza vaccinations. Long-term prophylactic antibiotics may be given in certain cases.

As an adaptation

An enlarged spleen may be an inherited, adaptive trait selected in populations that need extra oxygen carry capacity such as deep sea divers. The Sama-Bajau people, notable for free-diving, have spleens that are 50% larger than those of nearby ethnic groups.

References

References

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