Infectious Mononucleosis

Infectious Mononucleosis (Glandular Fever). This is a benign febrile disease characterized by lymphadenopathy and lymphocytosis. It is probably of viral origin, with a portal of entry through the naso­pharynx and cervical lymph nodes. It has been described in the Hematology section. Splenic enlargement is present in 50 per cent of the cases and rupture of the spleen may occur in rare instances.

Infectious Splenomegaly

Hyperplasia of the spleen with infectious disease may be acute or chronic. Acute hyperplastic splenitis (acute splenic tumor) occurs with septicemia or in the presence of severe pyogenic infections. The spleen is enlarged and soft. The follicles may be enlarged and phagocytosis is active.
In protozoan and bacterial diseases that affect the reticuloendothelial system, such as visceral leishmaniasis, African trypanosomiasis, malaria, etc., the enlarged spleen acts as a clearing house for phagocytosis and is engorged with parasites and para­sitized macrophages.With chronic splenic hyperplasia found in advanced stages of syphilis, tuberculosis, brucellosis, malaria, leishmaniasis, trypanosomiasis, schistosomiasis and infectious ar­thritis (Felty's syndrome) there is increase of both the lymphoid and connective tissue elements. The capsule is often thick and opaque. There may be endothelial hyper­plasia and hyalin changes in the arterioles. The infectious diseases of the spleen and reticuloendothelial system are:

(1)Infectious mono nucleosis
(2)Brucellosis
(3)Sarcoidosis
(4)Visceral leish maniasis
(5)Malaria
(6)Bartonellosis
(7) Histoplasmosis
(8)Toxoplasmosis
(9)Schistosomiasis
(10) Trypanosomiasis(11)Relapsing fever
(12)Melioidosis and Glanders

Congestive Splenomegaly

Passive congestion of the spleen occurs with cardiac decompensation. The spleen is enlarged and firm because of the retention of blood in the pulp sinusoids.In Banti's syndrome more severe congestive splenomegaly occurs with portal hyper­tension. The retained blood dilates the sinusoids and thickens their walls. Increased blood destruction leads to anemia and leukopenia. The condition may result from hepatic cirrhosis or from pressure on or thrombosis in the portal or splenic veins. These are associated with gastric hemorrhages. In such cases anemia is relieved by splenectomy, but the gastrointestinal hem­orrhages may recur.