Fiser Chapter 34 SPLEEN Flashcards
Splenic arteries
Splenic and short gastrics (end arteries), left gastroepiploic
Splenic vein location
Posterior and inferior to splenic artery
Goes into portal vein
Speen function
Reservoir for platelets
Ag-processing center for macrophages
Largest producer of IgM
Red pulp (85%): filter for aged or damaged RBCs
White pulp (15%): immunologic, contains lymphocytes and macrophages
Hematopoiesis before birth and in myeloid dysplasia
Red pulp
filter for aged or damaged RBCs
Pitting: removal of abnormalities in RBC membrane
Howell-Jolly bodies- nuclear remnants
Heinz bodies- hemoglobin
Culling: removal of less deformable RBCs
White pulp
Immunologic function; contains lymphocytes and macrophages
Major site of bacterial clearance that lacks preexisting Abs
Site of removal of poorly opsonized bacteria, particles, debris
Ag processing occurs with interaction between macrophages and helper T cells
Tuftsin
An opsonin that facilitates phagocytosis and is produced in spleen
Properdin
Activates alternate complement pathway, produced in spleen
Accessory spleen most commonly found where
Splenic hilum
Occurs in 20%
Splenectomy indications
Trauma ITP >> TTP Hypersplenism Hereditary spherocytosis Pyruvate kinase deficiency G6PD deficiency (sometimes) Beta thalassemia (if splenomegaly) Warm antibody-type acquired immune hemolytic anemia Lymphomas Splenic sarcoidosis Felty's syndrome Splenectomy Splenic cysts
ITP pathophysiology
Anti-platelet IgG binds platelets
Petechiae, gingival bleeding, bruising, soft tissue ecchymosis
Normal spleen
Tx: steroids, gammaglobulin if steroid resistant, splenectomy for those who fail steroids
How does splenectomy help ITP?
Removes IgG production and source of phagocytosis
Give platelets 1 hour before surgery
80% response; Avoid splenectomy in children < 10 years, will usually resolve spontaneously; At least wait until 5 so they have Ab’s
TTP pathophysiology
Loss of platelet inhibition leads to thrombosis and infarction -> profound thrombocytopenia
Purpura, fever, AMS, renal dysfunction, hematuria, hemolytic anemia
Tx: Plasmapheresis; immunosuppression; 80% respond to medical tx; splenectomy RARELY indicated
Death from intracerebral hemorrhage or ARF
Risk of post-splenectomy sepsis syndrome
Most episodes occur within 2 years after splenectomy
0.1%
Children have higher risk and mortality
Higher in hemolytic disorders or malignancy
Post-splenectomy sepsis syndrome bacteria
SHiN: S pneumonia, H influenza, N meningitides
Post-splenectomy sepsis syndrome pathophysiology
Lack of IgM to capsulated bacteria
Vaccines needed before splenectomy
Pneumococcus
Meningococcus
H influenza
Hypersplenism definition
-Decreased circulating cell count of erythrocytes and/or platelets and/or leukocytes
-Normal compensatory hematopoietic response in BM
-Correction of cytopenia by splenectomy
+/- Splenomegaly
Spherocytosis
- Most common congenital hemolytic anemia requiring splenectomy
- Spectrin deficit (membrane protein) deforms RBCs and leads to splenic sequestration (hypersplenism)
- Causes pigmented stones, anemia, reticulocytosis, jaundice, splenomegaly
- Tx: Splenectomy and Cholecystectomy; curative
Elliptocytosis
Similar to but less common that spherocytosis
-Spectrin and protein 4.1 deficit (membrane protein)
Pyruvate kinase deficiency
Altered glucose metabolism
- -> congenital hemolytic anemia
- -> RBC survival enhanced by splenectomy
Most common congenital hemolytic anemia NOT involving membrane protein that requires splenectomy
G6PD deficiency
Splenectomy usually not required
Causes of spontaneous splenic rupture
Mononucleosis Malaria Sepsis Sarcoid Leukemia Polycythemia vera
What is splenosis
Splenic implants
Usually related to trauma
Results of splenectomy/hyposplenism
Howell-Jolly bodies (nuclear fragments) Heinz bodies (Hgb deposits) Pappenheimer bodies (iron deposits) Target cells Spur cells (acanthocytes) Transient thrombocytosis Transient leukocytosis Persistent lymphocytosis Persistent monocytosis
Most common cause of splenic artery or splenic vein thrombosis?
Pancreatitis
Postsplenectomy changes in blood
Increased RBCs
Increased WBCs
Increased platelets: if > 1 x 10^6, give ASA
Most common splenic tumors
Benign: Hemangioma (most common overall)
Malignant: Non-Hodgkin’s lymphoma
Guidelines for prevention of ppostplenic sepsis
- If possible vaccinate with polyvalent pneumococcal vaccine at least 10-14 days prior to splenectomy
- If urgent, wait at least 14 days postop to vaccinate
- Also meningococcal and H influenza vaccine for high-risk patients (immunosuppressed of children <10yo)
- Abx ppx for children <5yo
- Early Abx for initial signs of infection
- MedicAlert bracelet
