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Spleen MCQ

1. As the functional anatomy of the spleen is divided into red pulp, white pulp, and marginal zone, what function is incorporated into the anatomy of the cortical zone that relates to infection control?
A. Filtration of red cells, encapsulated bacteria, and other foreign material.
B. Red pulp for formation of red cells.
C. White pulp for its role in formation of granulocytes.
D. Gray areas, so formed because of the production of platelets.
E. Fibrous trabeculae.
Answer: A


DISCUSSION: The cortical networks described by Billroth are lined with B-, T-, and other lymphocyte
subpopulations. The open zones, called by some the cords of Billroth, serve as an anatomic microfilter as well as a functional mechanism for removing foreign materials. For example, immature red cells with retained nuclei are “pitted” by these cords and removed from circulation. Pneumococcal and other bacteria (encapsulated and nonencapsulated) can be removed by the spleen. The filter mechanism of the spleen, combined with this immune capacity, is what is mainly lost in splenectomy that exposes the asplenic patient to overwhelming postsplenectomy sepsis syndrome (OPSS).




2. During the evolution of the understanding of hematologic diseases, the indications for splenectomy have changed. The most common indications for splenectomy are, in descending order of frequency:
A. Traumatic injury, immune thrombocytopenia, hypersplenism.
B. Immune thrombocytopenic purpura, traumatic injury, hypersplenism.
C. Hypersplenism, traumatic injury, immune thrombocytopenia.
D. Immune thrombocytopenia, hypersplenism, traumatic injury.
E. None of the above.
Answer: A


DISCUSSION: Over the years, the indications for splenectomy have varied as better understanding and altered therapy for immune system diseases have occurred. Whereas in the past splenectomy was the available therapy for hypersplenism, better understanding of the diseases causing hypersplenism (which is a syndrome) has allowed other therapies to emerge. Splenectomy, therefore, is less often required for the treatment of hypersplenism associated with some types of hematologic malignancies. Traumatic injury remains the most common indication for splenectomy, although this situation may change as conservative management of splenic injuries continues to increase. Moreover, immune thrombocytopenia is increasing in frequency and is definitively cured by splenectomy.




3. Useful methods for detection of splenic injury, in descending order of sensitivity, are:
A. Diagnostic peritoneal lavage.
B. CT.
C. Ultrasonography.
D. Isotope scan.
E. Magnetic resonance imaging (MRI).
Answer: B


DISCUSSION: Diagnosis of splenic injury is most specifically made and quantitated by CT. Diagnostic peritoneal lavage is useful for detecting intra-abdominal bleeding, but not specific to splenic injury. Isotope scans are useful to a point but do not delineate the anatomy of the spleen that is injured. Classifications of splenic injury are currently being developed based on the images provided by CT scans and are evolving into prospective decision trees for operation or conservative management.




4. The following statements about splenosis are correct:
A. Autotransplantation of splenic tissue is an etiology.
B. May protect against OPSS.
C. May over time be “born again” and regain some immune function.
D. May produce tuftsin and properdin.
E. All of the above.
Answer: E


DISCUSSION: Splenosis or autotransplantation of splenic tissue, which may follow splenic injury, can result in the return of some types of immune function. The “born again” spleen refers to the detection in blood samples of the opsonin tuftsin and properdin, which have been observed to occur in the occasional patient at a period of time remote from splenic injury. The supposition is that as the splenic implants grow and multiply in time, they reach a critical mass whereby opsonins may be formed and presumably the implants can provide some of the host defense mechanisms that were lost with splenectomy.




5. The following comments about immune thrombocytopenic purpura (ITP) are accurate:
A. Platelet count is low.
B. Circulating antiplatelet factor is present.
C. Antiplatelet factor is immunoglobulin G (IgG) antibody.
D. Purpura is directed against a platelet-associated antigen.
E. May be fatal.
F. All of the above.
Answer: A


DISCUSSION: ITP is a disease characterized by low platelet counts and a bone marrow with proliferative megakaryocytes. The disease is usually diagnosed by abnormal episodes of bleeding, which may occur from trauma, menses, etc. The causative event by which sensitized platelet-associated antibodies are developed is probably multiple. The effect of the platelet-associated antibodies, which is usually IgG, is directed against a platelet-associated antigen and, when coating of normal platelets occurs, results in the platelets being sequestered from the system by the reticuloendothelial system with resultant thrombocytopenia.




6. ITP:
A. Is most common in men in their 20s.
B. Is frequently cured in adults by corticosteroid administration.
C. Usually requires splenectomy in children.
D. Is most common in the sixth decade of life.
E. Is in remission in more than 80% of patients with splenectomy.
Answer: E


DISCUSSION: ITP is characterized by a low platelet count and is definitively diagnosed by low platelet count in association with bone marrow that shows thrombasthenia. Patients with this illness experience abnormal bleeding during menstruation or nosebleeds or in response to minor insults. Occasionally, a patient who bleeds excessively after an auto accident is found to have undiagnosed ITP. The usual therapy is initiated with prednisone, and some believe that the prednisone response is predictive of success after splenectomy. Approximately 80% of patients, however, require increasing doses of steroids to maintain satisfactory platelet counts and ultimately require splenectomy. Similarly, approximately 80% of patients achieve normal platelet counts within 3 months after splenectomy, whereas more than 90% are remitted from further bleeding episodes.




7. Splenectomy and perioperative therapy for ITP:
A. Follow successful steroid therapy.
B. Respond permanently to high-dose intravenous gamma globulin.
C. Are best preceded by polyvalent vaccines for Pneumococcus, Haemophilus influenzae, and Neisseria meningitidis.
D. Cannot be done laparoscopically.
E. Are associated with splenomegaly.
Answer: C


8. Thrombotic thrombocytopenic purpura (TTP) is a syndrome characterized by all of the following except:
A. Thrombocytopenia.
B. Microangiopathic hemolytic anemia.
C. Deposition of platelet microthrombi.
D. Fluctuating neurologic abnormalities.
E. Renal failure.
F. Afebrile.
Answer: F


DISCUSSION: This disease, sometimes called Moschcowitz's syndrome, is characterized by thrombocytopenia, microangiopathy, chemolytic anemia, fluctuating neurologic abnormalities, progressive renal failure, and fever. Platelet deposits, with hyaline material composed of aggregated platelets and fibrin, occur. The cause is unknown, and the prognosis is very poor: survival is less than 10%. A combined approach using antiplatelet drugs and corticosteroids can be effective and sometimes has improved results if done with splenectomy.




9. Which of the following comments does not describe hypersplenism?
A. It may occur without underlying disease identification.
B. It may be secondary to many hematologic illnesses.
C. It is associated with work hypertrophy from immune response.
D. It requires evaluation of the myeloproliferation.
E. It is associated with antibodies against platelets.
Answer: E


DISCUSSION: Hypersplenism was described by Chauffard in 1907 and initially was mostly associated with the syndrome in which a variety of hematologic illnesses, ranging from sickle cell disease to the leukemias, could be found to have improved circulating blood elements if the spleen were removed. Diagnosis of these illnesses has improved, and illnesses once classified as primary hypersplenism now are frequently classified as secondary, as the primary mechanism involved is known. The spleen may enlarge owing to differing pathophysiologic mechanisms, but when it achieves a certain size, it removes all of the main circulating cellular blood elements (red blood cells, white blood cells, platelets). One element may be more deficient than others.




10. Hyposplenism is a potentially lethal syndrome. Which of the following statements is incorrect?
A. It is confirmed by isotope scan.
B. It is always associated with an atrophic spleen.
C. It may be associated with overwhelming post-splenectomy sepsis syndrome (OPSS).
D. It is associated with thyrotoxicosis, corticosteroid administration, and some contrast agents.
E. It may be associated with ulcerative colitis or sickle cell anemia.
Answer: B




11. Hodgkin's disease is a malignant lymphoma with four histologic subtypes. Which of the following is not one of the subtypes?
A. Lymphocyte predominance.
B. Nodular sclerosis.
C. Mixed cellularity.
D. Lymphocyte depletion.
E. Leukocyte-lymphocyte dominance.
Answer: E


DISCUSSION: A variety of histologic conventions for the major subtypes of Hodgkin's disease have been derived over the years. They are useful in identifying the prognosis and predictions for morbidity and mortality. The subtypes are further subdivided to provide more precise association with therapeutic approaches, with identification with various staging levels, etc.




12. Which of the following statements about lymphatic capillaries are true?
A. These vessels have delicate tricuspid valves every 2 to 3 mm.
B. Lymphatic capillaries are more permeable than blood capillaries.
C. Lymphatic capillaries are less permeable than blood capillaries.
D. Lymphatic capillaries contain gaps large enough to admit particles as large as lymphocytes.
Answer: CD


DISCUSSION: The transporting lymphatic vessels have valves but lymphatic capillaries do not. The lymphatic capillaries will accept particles including bacteria, red blood cells, and lymphocytes and transport them to regional lymph nodes.




13. Which of the following forces do not promote the formation of interstitial fluid?
A. Increased venous pressure.
B. Constrictive pericarditis.
C. Hypernatremia.
D. Hypoproteinemia.
Answer: C


DISCUSSION: Interstitial fluid production is a function of the hydrostatic and colloid osmotic pressures across the capillary membrane. Forces tending to increase interstitial fluid flux across the capillary membrane include obstruction to outflow of the capillary due to structural or functional obstruction in the venous system or increase in venous pressure from any cause, reduction in osmotic pressure due to hypoproteinemia, and increase in pore size due to local mediators of inflammation.




14. The most frequent cause of primary lymphedema is:
A. A deficiency of transporting lymphatic channels.
B. Valvular incompetence in lymphatic channels.
C. Obstruction or removal of regional lymph nodes.
D. Thrombosis of lymphatic channels.
Answer: A


DISCUSSION: Primary lymphedema is most frequently due to hypoplasia or aplasia of extremity transporting lymphatic channels.




15. Most patients with lymphedema can be managed by:
A. Pedicle transfer of lymphatic bearing tissue into the affected area.
B. Elevation, elastic support garments, and massage therapy or mechanical pneumatic compression.
C. Lymphatic bypass using an autogenous vein graft.
D. Excision of hypertrophic scarred fibrotic skin and subcutaneous tissue down to muscle fascia and coverage with split-thickness skin grafts.
Answer: B


DISCUSSION: The vast majority of patients with mild to moderate lymphedema can be managed with leg elevation and elastic support garments, and some will require mechanical pneumatic compression or massage therapy. Only patients with very severe deforming elephantiasis require operative therapy.




16. Which statements about lymphangiomas are true?
A. Most lesions appear during puberty.
B. These lesions frequently respond to small doses of radiation therapy.
C. The lesions usually grow slowly but may infiltrate local tissues.
D. Malignant transformation is frequent.
Answer: C


DISCUSSION: Lymphangiomas are congenital malformations of the lymphatic vessels. Most appear at birth or during early infancy. The lesions grow slowly and infiltrate local tissues, but actual malignant degeneration is exceedingly rare. The lesions are not responsive to radiation therapy.




17. The two primary causes of death from sickle cell disease in the first decade of life are which of the following?


a. Sepsis
b. Splenic sequestration crisis
c. Acute chest syndrome
d. Heart failure
Answer: a, b


Sickle cell disease and thalassemia are the principal hemoglobinopathies that cause clinically important disease. Clinical symptoms are directly dependent upon the amount of HgbS present, and this is variable. Patients who are homozygous for HgbS usually have small sequential splenic infarcts as a result of microvascular occlusion and the spleen usually becomes small, fibrotic, and dysfunctional by the age of 5 years. Splenic sequestration crisis is a cause of anemia that can be acute and life-threatening. Sepsis associated with functional asplenia can be lethal as well. These are the two primary causes of death in sickle cell disease during the first decade of life.




18. The best therapy for a patient with thrombotic thrombocytopenic purpura is which of the following:


a. Plasmapheresis
b. Corticosteroids
c. Splenectomy
d. Intravenous immune globulin
Answer: a


Thrombotic thrombocytopenic purpura (TPP) is a relatively rare syndrome with no definitive diagnostic test or clinical characteristic. The principal clinical features are thrombocytopenic purpura, fever, microangiopathic hemolytic anemia, mental status changes, and renal dysfunction. Treatment is generally focused on the removal of the plasma constituents that lead to platelet aggregation. Plasmapheresis is particularly effective and has decreased the 1-year mortality rate of 50% to 80% to about 10%. Splenectomy was initially proposed for TPP but has been shown to have little benefit and instead is associated with a considerable risk of postsplenectomy sepsis. Corticosteroids and intravenous immune globulin are appropriate therapies for immune thrombocytopenic purpura (ITP), but not TPP.




19. Which of the following statements regarding post splenectomy sepsis are true?


a. The incidence in children is generally reported as less than 5%
b. Haemophilus influenzae, Streptococcus pneumoniae and Neiseria meningitidis are the most common causative organisms
c. Autotransplantation techniques eliminate this risk
d. The mortality rate is now approximately 50%
e. The incidence in adults in approximately 1%
Answer: a, b, d, e


Postsplenectomy sepsis (PSS) refers to the increased risk of systemic infection in patients who have undergone splenectomy. The incidence of PSS in children is as high as 4% during a follow-up of nearly 10 years, and from 0.3% to 1.8% in adults during an 8-year follow-up. The highest incidence of PSS is among those who have undergone splenectomy for associated malignancies or who had an incidental splenectomy during other surgical procedures in adulthood. In children, the patients most at risk for PSS are those who have undergone splenectomy for either congenital or acquired anemias. It is important to remember that any patient who has undergone splenectomy or who has hyposplenism is at risk for PSS.
The most common causative organisms are Streptococcus pneumoniae, Haemophilus influenzae, and Neiseria meningitidis. Other less common encapsulated organisms have also been identified. In addition, organisms without classical polysaccharide cell walls can occasionally produce overwhelming infection in postsplenectomy patients. The mortality from PSS is approximately 50%. Splenic autotransplantation has been proposed as an alternative means of splenic preservation in patients whose spleens are too severely injured for in situ repair. Splenic autotransplants do not appear to have normal splenic function. Splenic autotransplants have diminished ability to protect against PSS when compared to a normal spleen and they have not been demonstrated to prevent post-splenectomy sepsis.




20. You are consulted regarding a 50-year old male with Laennec’s cirrhosis, portal hypertension and hypersplenism. He has no history of gastrointestinal bleeding. You would recommend which of the following?


a. Splenectomy
b. Prophylactic sclerotherapy for esophageal varices
c. Portosystemic shunt
d. Observation
Answer: d


Patients with hypersplenism from portal hypertension usually present with thrombocytopenia as the primary manifestation. The role of splenectomy in such patients is controversial. Although splenectomy may transiently increase the number of platelets in the peripheral circulation, it generally does not improve survival. At the time of surgery, these patients have considerable risk for massive bleeding and subsequent complications related to hepatic dysfunction. These latter complications include ascites, coagulopathy, and wound complications. The severity of the underlying liver disease is the determining factor for these patients. Some believe that splenectomy is contraindicated in patients with portal hypertension. Indeed, the perioperative risks are considerably greater than normal. This should be considered as a last option, and even then with the realization that the operative and preoperative morbidity and mortality are high.
In the absence of gastrointestinal bleeding, this particular patient has no indication for either sclerotherapy or portosystemic shunting.




21. Glucose-6-phosphate dehydrogenase (G6PD) deficiency is an abnormality of erythrocyte metabolism associated with hemolytic anemia. Pharmocologic agents which induce hemolysis include which of the following?


a. Acetylsalicylic acid
b. Vitamin E
c. Sulfamethoxazole
d. Desferrioxamine
e. Nitrofurantoin
Answer: a, c, e


Generally, G6PD deficiency is not clinically apparent; hemolytic anemia occurs in most patients only after the consumption of certain medications or exposure to specific chemicals. A partial list of oxidizing agents known to induce acute hemolytic anemia in patients with G6PD deficiency follows:
Acetylsalicylic acid (high dose)
Phenacetin
Nitrofurantoin
Sulfamethoxazole
Doxorubicin
Nalidixic acid
Acetanilid
Primaquine
Phenazopyridine
Methylene blue
Niridazole
Furazolidone
Fava beans
Splenectomy is rarely indicated in patients with G6PD deficiency. Management generally is adequate simply by avoiding exposure to precipitating agents. Vitamin E and desferrioxamine may be therapeutic for G6PD deficient patients, presumably related to their antioxidant activity.




22. Hypersplenism is associated with which of the following diseases?


a. Portal hypertension
b. Lymphoma
c. Mononucleosis
d. Systemic lupus erythematosus
e. Gaucher disease
Answer: a, b, c, d, e


Hypersplenism is not a specific disease but rather a physiologic state characterized by splenomegaly, a decrease in circulating levels of some blood cells or platelets, bone marrow hypertrophy in response to the decrease in the circulating blood elements, and some degree of improvement by splenectomy. Disease processes associated with secondary hypersplenism include the following:
INCREASED VENOUS PRESSURE
Portal hypertension
Splenic vein thrombosis
Severe congestive heart failure
MALIGNANCY
Leukemias (especially chronic)
Lymphoma
CHRONIC INFLAMMATORY DISEASES
Felty syndrome
Systemic lupus erythematosus
Sarcoidosis
METABOLIC ABNORMALITIES
Amyloidosis
Gaucher disease
Niemann-Pick disease
INFECTION
Mononucleosis
Bacterial endocarditis
Parasites
Fungus
OTHER
Myelofibrosis with myeloid metaplasia
Polycythemia vera




23. A 40-year old woman with chronic immune thrombocytopenic purpura (ITP) is refractory to corticosteroids. The approximate likelihood she will benefit from a splenectomy is approximately which of the following?


a. Less than 20%
b. 40%
c. 60%
d. 80%
Answer: c


Splenectomy remains the principal treatment for ITP. Platelet counts rise to adequate levels in 60% to 80% of patients who undergo the procedure. Ninety percent of patients who have had good responses to corticosteroids have improved platelet counts after splenectomy. Of patients who do not respond to corticosteroids, about 60% respond to splenectomy. Splenectomy is effective by virtue of its ability to remove the site of platelet destruction. Because the spleen is the site of most platelet sequestration in ITP, splenectomy should eliminate this source of platelet consumption. Furthermore, splenectomy removes a significant source of antiplatelet IgG production.




24. Which of the following statements regarding splenic function in humans are true?


a. The specific immune function of the spleen is principally related to its antigen processing role
b. The spleen is the major site of synthesis of complement pathway proteins
c. The spleen is more efficient than the liver at removing bacteria with a high density of surface opsonins
d. The spleen serves as a principal source of nonspecific opsonins
Answer: a, d


Immune function of the spleen includes both nonspecific and specific immune responses. Nonspecific immune function is largely characterized by removal of particulate matter by the macrophages. The spleen contains 25% of the fixed tissue macrophage population in the body. The spleen is more efficient than the liver at removal of incompletely opsonized bacteria. The liver is most effective at removing bacteria with a high density of surface opsonins. The spleen also serves as a principal source of nonspecific opsonins. These include tuftsin, properidin, and fibronectin. Tuftsin stimulates granulocyte and macrophage motility and phagocytosis. Properdin activates the alternative pathway of the complement system, leading to complement fixation. Both the activated complement complexes and the complement products facilitate the destruction of the target organism. Fibronectin is a macromolecule that appears to have nonspecific stimulatory activity on the processes of fibrosis and wound healing.
The specific immune functions of the spleen are principally related to its antigen-processing role, and this is in turn dependent on its unique anatomy and the circulation of lymphocytes into the spleen.
The liver, not the spleen, is the major site of synthesis of complement pathway proteins.

1 comment:

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