PATHO - WBC and Lymph Nodes 5 (Spleen and Thymus)

150 grams

What is the normal adult weight of the spleen?

Connective tissue capsule

What covers the spleen externally?

Slate-gray

What color describes the spleen’s capsule on gross examination?

Red pulp

What pulp of the spleen contains vascular sinusoids and cords of Billroth?

White pulp

What pulp of the spleen contains the periarteriolar lymphatic sheath?

T lymphocytes

What type of lymphocytes are found in the periarteriolar lymphatic sheath?

Germinal center

What lymphoid structure forms in the spleen during immune activation?

B lymphocytes

What cells predominantly compose splenic germinal centers?

Cords of Billroth

What are the splenic cords also called?

Sinusoids

What vascular structures separate the splenic cords?

Phagocytosis

What is the first major function of the spleen?

Antibody production

What is the second major function of the spleen?

Hematopoiesis

What is the third major function of the spleen?

Sequestration

What is the fourth major function of the spleen?

Deformation

What happens to RBCs as they pass through splenic sinusoids?

Phagocytosis

RBCs with decreased deformability are prone to what?

Macrophages

Which splenic cells phagocytose less deformable RBCs?

Pitting

What process describes removal of RBC inclusions by splenic macrophages?

Howell-Jolly bodies

What inclusion bodies may be removed during pitting?

Heinz bodies

What other inclusion bodies may be removed by pitting?

Bacteria

What type of foreign particles are removed by the spleen?

Dendritic cells

What cells trap antigens in the periarteriolar sheath?

Plasma cells

What cells produce antibodies in the spleen?

Polysaccharides

What type of microbial antigens stimulate splenic antibody formation?

Autoantibodies

What type of antibodies can the spleen also produce against self-antigens?

Fetal life

During which life stage does splenic hematopoiesis occur normally?

Severe chronic anemia

What condition reactivates splenic hematopoiesis in adults?

Extramedullary hematopoiesis

What term describes blood formation outside the marrow?

Cytopenia

What condition may result from splenic sequestration in splenomegaly?

Involvement in all

What is the spleen’s role in systemic inflammation and hematopoietic disorders?

Splenomegaly

What major manifestation occurs in splenic disorders?

Splenic insufficiency

What condition increases sepsis risk due to loss of phagocytosis and antibodies?

Encapsulated bacteria

What type of bacteria cause sepsis in splenic insufficiency?

Splenomegaly

What is the medical term for spleen enlargement?

Dragging sensation

What symptom may splenomegaly cause in the left upper quadrant?

Early satiety

What symptom may splenomegaly cause after eating?

Hypersplenism

What condition involves cytopenias due to splenic sequestration?

Anemia, leukopenia, thrombocytopenia

What triad characterizes hypersplenism?

Splenectomy

What surgery corrects cytopenia in hypersplenism?

Infectious endocarditis

Which infection causes nonspecific splenitis and endocarditis?

Infectious mononucleosis

Which viral infection classically causes splenomegaly in youth?

Tuberculosis

Which granulomatous infection can enlarge the spleen?

Typhoid fever

What enteric infection is linked to splenomegaly?

Brucellosis

Which zoonotic infection can cause splenic enlargement?

Cytomegalovirus

What herpesvirus may cause splenomegaly?

Syphilis

Which sexually transmitted infection may cause splenomegaly?

Malaria

Which parasitic disease is the most common cause of splenic enlargement worldwide?

Histoplasmosis

Which fungal infection can cause splenomegaly?

Leishmaniasis

Which parasitic infection causes “kala-azar”?

Schistosomiasis

What helminth infection causes “pipe-stem fibrosis”?

Gaucher disease

What disease causes splenomegaly due to Gaucher cells?

Niemann-Pick disease

Which storage disease accumulates sphingomyelin?

Systemic lupus erythematous

What autoimmune condition may cause splenic enlargement?

Rheumatoid arthritis

Which systemic inflammatory disorder can cause splenomegaly?

Hodgkin lymphoma

What hematologic malignancy is linked to splenomegaly?

Blood-borne infections

What causes nonspecific acute splenitis?

Congestion

What happens to red pulp in acute splenitis?

Necrosis

What happens to white pulp follicles during acute splenitis?

Hemolytic streptococcus

What bacterium often causes necrosis in acute splenitis?

Abscess

What rare complication may occur in acute splenitis?

Chronic venous obstruction

What causes congestive splenomegaly?

Liver cirrhosis

Most common intrahepatic cause of congestive splenomegaly?

Schistosomiasis

What parasitic disease directly causes pipe-stem fibrosis?

Portal vein thrombosis

What major vein obstruction causes extrahepatic splenomegaly?

Pancreatic tumors

Which abdominal tumors may cause splenic vein obstruction?

Firm, fibrotic capsule

Gross feature of congestive splenomegaly?

Fibrosis

Microscopic feature of long-standing congestive splenomegaly?

Systemic venous congestion

What cardiac condition causes moderate splenomegaly?

Splenic artery

What vessel occlusion causes splenic infarction?

No collaterals

Why are splenic infarcts often “bland”?

Infective endocarditis

What infection may cause septic infarcts?

Capsule

What direction does the infarct base face in the spleen?

Center

What direction does the infarct apex point?

Blunt trauma

What is the most common cause of splenic rupture?

Infectious mononucleosis

What infections predispose to spontaneous rupture?

Malaria

What tropical disease may cause fragile spleens?

Splenectomy

What surgical management prevents hemorrhage after rupture?

Fibrosis

Why are chronically enlarged spleens unlikely to rupture?

Hypoplasia

What term means underdeveloped spleen?

Aplasia

What term means absence of spleen?

Situs inversus

Aplasia of the spleen is associated with what congenital defect?

Spleniculi

What are accessory spleens called?

Hereditary spherocytosis

Spleniculi are clinically significant in which disease after splenectomy?

Normal spleen

What do spleniculi resemble microscopically?

Lymphoid and myeloid tumors

What tumors most commonly involve the spleen?

Hemangioma

Most common benign splenic tumor?

Lymphangioma

Second most common benign splenic tumor?

10-35 grams

What is the thymus weight at birth?

20-50 grams

What is the thymus weight at puberty?

5-15 grams

What is the thymus weight in adults?

Involution

What physiologic process decreases thymus size with age?

Polygonal

What shape are thymic epithelial cells in the cortex?

Spindle

What shape are thymic epithelial cells in the medulla?

Hassall corpuscles

What unique structure is found in the thymic medulla?

Keratinized cores

What do Hassall corpuscles contain in their centers?

Myoid cells

What specialized striated cells are present in thymus?

Myasthenia gravis

What disease links thymic myoid cells to autoimmunity?

DiGeorge syndrome

What syndrome causes thymic aplasia?

22q11 deletion

What chromosome deletion causes DiGeorge syndrome?

T-cell deficiency

What immune defect results from thymic aplasia?