Splenomegaly

Clinic

• Splenomegaly is one of the four cardinal signs of hypersplenism
• Splenomegaly is usually associated with increased workload (such as in hemolytic anemias)
• Other common causes include congestion due to portal hypertension and infiltration by leukemias and lymphomas.
• The most common causes of splenomegaly in developed countries are infectious mononucleosis, splenic infiltration with cancer cells from a hematological malignancy and portal hypertension (most commonly secondary to liver disease, and sarcoidosis). Splenomegaly may also come from bacterial infections, such as syphilis or an infection of the heart's inner lining (endocarditis). Splenomegaly also occurs in mammals parasitized by Cuterebra fontinella.

Pathophysiology

Splenomegaly can be classified based on its pathophysiologic mechanism:

• Congestive, by pooled blood (e.g., portal hypertension)
• Infiltrative, by invasion by cells foreign to the splenic environment (e.g., metastases, myeloid neoplasms, lipid storage diseases)
• Immune, by an increase in immunologic activity and subsequent hyperplasia (e.g., endocarditis, sarcoidosis, rheumatoid arthritis)
• Neoplastic, when resident immune cells originate a neoplasm (e.g., lymphoma).

Immune mediated causes

Response to infection (viral, bacterial, fungal, parasitic)	Disordered immunoregulation
Mononucleosis AIDS Viral hepatitis Subacute bacterial endocarditis, bacterial sepsis Splenic abscess, typhoid fever Brucellosis, Leptospirosis, MTB Histoplasmosis Malaria, Leishmaniasis, Trypanosomiasis Ehrlichiosis	RA including cases of Felty's syndrome SLE Serum sickness Familial hemophagocytic lymphohistiocytosis Autoimmune hemolytic anemia Autoimmune lymphoproliferative syndrome Sarcoidosis

Miasms

CLTV

CMV

CXA, CXB, ECHO

DHF

EBV

HAV

HBV

HCV

HHV-8

HIV

HSV-1

HSV-2

HTLV-1

MNGL

RBL

WNE