hyposplenisme

Hyposplenism refers to a condition characterized by reduced or impaired function of the spleen, despite its physical presence. The spleen plays a crucial role in filtering blood, removing old or damaged red blood cells, and acting as a reservoir for platelets and white blood cells. When its function is diminished, the body may struggle to clear abnormal or defective blood cells efficiently, leading to potential complications.

This condition can arise from various causes, including congenital anomalies, trauma, surgical removal (splenectomy), or diseases that impair splenic function such as infections (e.g., malaria or cytomegalovirus), certain cancers, or autoimmune disorders. Additionally, conditions like sickle cell disease or hereditary spherocytosis may contribute to splenic dysfunction over time.

One of the primary consequences of hyposplenism is an increased risk of *Howell-Jolly bodies*—small nuclear remnants of red blood cells that normally would be removed by a healthy spleen. Other abnormalities, such as target cells (acanthocytes) and increased numbers of platelet types, may also appear on blood smears. Patients with hyposplenism are particularly vulnerable to severe infections, particularly by encapsulated bacteria like *Streptococcus pneumoniae*, *Haemophilus influenzae*, and *Neisseria meningitidis*. This heightened susceptibility is due to the spleen’s role in opsonization, a process that enhances the ability of immune cells to recognize and destroy pathogens.

Diagnosis often involves identifying Howell-Jolly bodies on a peripheral blood smear, along with clinical suspicion based on the patient’s history. Imaging studies, such as ultrasound or CT scans, may help assess splenic size and structure. Treatment focuses on preventing infections through vaccination (e.g., pneumococcal, meningococcal, and *Haemophilus influenzae* type b vaccines) and, in some cases, prophylactic antibiotics. For individuals with a functional asplenic state, lifelong precautions are necessary to avoid life-threatening infections.