Spleen

Microscopic anatomy


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Red pulp

Red pulp is composed of splenic cords and sinuses (sinusoids).

White pulp


Spleen Manifestations in Disease

The spleen's primary roles are filtering blood and mounting immune responses. Its dysfunction or enlargement is a key sign of various systemic diseases. Spleen manifestations can be broadly categorized into Splenomegaly (enlargement) and Hyposplenism/Asplenia (decreased or absent function).

Splenomegaly (Enlarged Spleen)

Enlargement occurs via three main mechanisms:

  1. Congestion: Due to backup of blood.
  2. Infiltration: By abnormal cells (e.g., cancer, lipid-laden macrophages).
  3. Work Hypertrophy/Hyperplasia: Increased filtering or immune activity.

Clinical Presentation:

Key Causes & Associations:

Hyposplenism & Asplenia

This refers to decreased or absent splenic function, leading to impaired blood filtering and immune response.

Pathophysiology/Etiology:

Diagnosis (Hallmark Peripheral Smear Findings):

Complications & Management:

Disease Spleen Finding Mechanism
Sickle Cell Disease Splenomegaly (in children) -> Autosplenectomy (in adults) Vaso-occlusion from sickled RBCs causes initial splenic sequestration crisis, followed by recurrent infarctions leading to a shrunken, fibrotic spleen.
Hereditary Spherocytosis Splenomegaly "Work hypertrophy" from clearing spherocytic RBCs. Splenectomy is curative.
Infectious Mononucleosis (EBV) Splenomegaly Lymphoid hyperplasia in response to viral infection. High risk of rupture.
Portal Hypertension Congestive Splenomegaly Increased pressure in the splenic vein obstructs outflow.
Myelofibrosis Massive Splenomegaly Extramedullary hematopoiesis (blood cell production shifts to spleen as bone marrow fails).
Hairy Cell Leukemia Massive Splenomegaly Infiltration of the red pulp by neoplastic B-cells.
ITP Normal Spleen Size or Mild Splenomegaly Spleen is the site of platelet destruction, but does not typically cause significant enlargement.