Splenomegaly, or an enlarged spleen, arises through different pathogenic mechanisms which can be broadly classified. According to the provided reference, these mechanisms fall into two main categories: Congestive and Infiltrative.
Pathophysiologic Mechanisms of Splenomegaly
| Mechanism | Description | Example |
|---|---|---|
| Congestive | Increased blood pooling in the spleen due to impaired outflow. | Portal hypertension |
| Infiltrative | Invasion of the spleen by foreign cells, disrupting normal splenic architecture and function. | Metastases, myeloid neoplasms, lipid storage diseases |
Congestive Splenomegaly
Congestive splenomegaly occurs when blood flow out of the spleen is obstructed, leading to a backup of blood within the organ. This increased blood volume causes the spleen to enlarge. A prime example of this is portal hypertension.
- Portal Hypertension: Elevated pressure in the portal vein (which carries blood from the digestive organs to the liver) causes blood to back up into the spleen, leading to congestion and enlargement.
Infiltrative Splenomegaly
Infiltrative splenomegaly happens when the spleen is infiltrated by abnormal cells. These cells take up space and disrupt the normal splenic tissue, causing enlargement.
- Metastases: Cancer cells from other parts of the body can spread to the spleen and proliferate, causing it to enlarge.
- Myeloid Neoplasms: Diseases like leukemia and myeloproliferative disorders involve the abnormal production and accumulation of blood cells in the spleen.
- Lipid Storage Diseases: Genetic disorders where lipids accumulate in cells, including those in the spleen, leading to its enlargement.
In summary, the pathogenesis of splenomegaly involves either an increase in blood pooling due to congestion or infiltration by abnormal cells, disrupting the spleen's normal structure and function.
