Corpus: Asplenia

Asplenia refers to an anatomical or functional absence of the spleen. A partial loss of function is called hyposplenia.

• ICD10 codes: D73.0, Q89.0

The spleen is where the breakdown of erythrocytes takes place (cell moulting). It also plays an important role in the immune system. In particular, the spleen is indispensable for the defence against infections with encapsulated bacteria, fungi or parasites.

A distinction is made between congenital and acquired asplenia.

Acquired asplenia[Bearbeiten]

The most common cause (> 90%) of acquired asplenia is splenectomy, which is performed e.g. as part of a traumatic splenic rupture or electively in severe haemolytic anaemia (sickle cell anaemia, globular cell anaemia) or thrombocytopenia (ITP).

The spleen can also atrophy without surgical intervention and be replaced by functionless scar tissue. In this case, it is referred to as an autosplenectomy. It occurs, for example, after multiple splenic infarctions.

Functional asplenia occurs when the organ function of the spleen is severely impaired despite preserved anatomy. Possible causes are

• Sickle cell anaemia
• Autoimmune diseases (SLE)
• amyloidosis
• Stem cell transplantation (graft-versus-host reaction)

Congenital asplenia[Bearbeiten]

Congenital absence of the spleen is very rare. It occurs in isolation as congenital familial isolated asplenia or as part of syndromes, e.g. Ivemark syndrome.

Patients with asplenia suffer from an increased susceptibility to infection, as the spleen as an important lymphatic organ is absent. The clearance of bacteraemia and fungemia is significantly reduced, as macrophages normally eliminate IgG-labelled and encapsulated pathogens in the meshwork of the spleen tissue. This effect is particularly pronounced in infants and small children.

The formation of IgM antibodies is also impaired. There are significantly fewer IgM antibodies in the blood and fewer memory B cells that produce IgM. This also reduces the effect of vaccinations.

A severe septic clinical picture that can occur with asplenia is OPSI syndrome.

Asplenia can be diagnosed in the laboratory if Howell-Jolly bodies can be seen in the erythrocytes in the blood smear. Lymphocytosis and a reduced formation of IgG and IgM may also occur.

Morphological changes in the spleen (fibrosis, involution, haemorrhages) can be seen on imaging. Sonography, abdominal CT or abdominal MRI can be considered.

In the case of asplenia, vaccinations against encapsulated pathogens are necessary, in particular against

• Pneumococci: pneumococcal vaccination
• Meningococci: meningococcal vaccination against serogroups ACWY and possibly B
• Haemophilus influenzae (type b)

In addition, an annual vaccination against influenza is advisable.

Early antibiotic therapy is recommended for febrile infections.