Accessory spleen

Accessory spleen
Synonyms	Splenunculus, supernumerary spleen
Pronounce	N/A
Specialty	N/A
Symptoms	Usually asymptomatic, may cause abdominal pain if torsion occurs
Complications	Splenic torsion, infarction
Onset	Congenital
Duration	Lifelong
Types	N/A
Causes	Developmental anomaly
Risks	None specific, incidental finding
Diagnosis	Ultrasound, CT scan, MRI
Differential diagnosis	Splenosis, lymphadenopathy, neoplasm
Prevention	N/A
Treatment	Usually none required, surgery if symptomatic
Medication	N/A
Prognosis	Excellent if asymptomatic
Frequency	Found in approximately 10-30% of the population
Deaths	N/A

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  Gross pathology of an accessory spleen

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  Photomicrograph of a splenunculus

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  Accessory spleen (Nebenmilz)

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  Hypertrophic accessory spleen with hematoma

An accessory spleen is a small nodule of splenic tissue that is separate from the main body of the spleen. It is a common congenital anomaly, occurring in approximately 10-30% of the population. Accessory spleens are usually asymptomatic and are often discovered incidentally during imaging studies or surgical procedures.

Anatomy and Location

Accessory spleens are typically found near the hilum of the spleen, but they can also be located in other areas of the abdominal cavity, such as the pancreas, omentum, or mesentery. They are usually small, ranging from a few millimeters to a few centimeters in diameter.

Development

Accessory spleens develop during embryogenesis when splenic tissue becomes separated from the main body of the spleen. This can occur due to incomplete fusion of the splenic anlage or due to the presence of multiple splenic nodules during development.

Clinical Significance

While accessory spleens are generally benign and asymptomatic, they can become clinically significant in certain situations. For example, in patients undergoing splenectomy for conditions such as idiopathic thrombocytopenic purpura (ITP), an accessory spleen can continue to produce platelets, potentially leading to a recurrence of symptoms. In such cases, identification and removal of the accessory spleen may be necessary.

Diagnosis

Accessory spleens are often identified through imaging studies such as computed tomography (CT) scans, magnetic resonance imaging (MRI), or ultrasound. On imaging, they appear as well-defined, homogeneous nodules with similar characteristics to the main spleen.

Treatment

In most cases, accessory spleens do not require treatment. However, if they cause symptoms or complications, surgical removal may be indicated. This is typically done laparoscopically.

Related Pages

• Spleen
• Splenectomy
• Idiopathic thrombocytopenic purpura
• Congenital anomalies