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The Spleen
Anatomy
of Spleen
White Pulp
Spleen Structure
The white pulp is circular in
structure and is made up mainly
of lymphocytes. It functions in a
manner similar to the nodules of the
lymph node.
The red pulp surrounds the white
pulp and contains mainly red blood
cells and macrophages. The main
function of the red pulp is to
phagocytize old red blood cells.
Red Pulp
Function

The spleen is a sophisticated filter that monitors
and manages blood cells and immune functions
 During fetal development the spleen produces red
and white blood cells
 By the fifth month of gestation the spleen no
longer has hematopoietic function but retains the
capacity throughout life
 Red cells that pass through the spleen undergo a
“cleaning” or repair
 Abnormal and old cells are destroyed
Function

Reticulocytes loose their nuclear remnants
and excess membrane before entering the
circulation
 RBC’s coated with IgG and IgM are removed
and destroyed
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The spleen is the site of destruction in
autoimmune disease states (ITTP and hemolytic
anemia)
Parasites such as malaria can be removed as well
The spleen is involved in specific and
nonspecific immune responses (promotes
phagocytosis and destruction of bacteria)
Sites of Haemopoiesis

Yolk sac

Liver and spleen

Bone marrow


Gradual replacement of
active (red) marrow by
tissue inactive (fatty)
Expansion can occur
during increased need
for cell production
Splenic Trauma

Diagnosis

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Injury should be suspected in blunt upper
abdominal injuries ( MVA and Bike)
Injuries are often associated with fractured ribs of
the left chest
Splenic injuries can cause extensive and
continued hemorrhage, others can cause
subcapsular hematomas that are subject to
rupture at any time
If splenic injury is suspected, admission to the
hospital for monitoring is mandatory
The signs and symptoms of splenic trauma are
those of hemoperitoneum (generalized LUQ pain)
Treatment of Ruptured Spleen
 Splenic
preservation operations
 Partial splenectomy
 Capsular repair
 Non operative treatment
Delayed Rupture of the
Spleen

Injury to the pulp sometimes cannot be
contained indefinitely by the splenic capsule
 The usual interval between injury and
hemorrhage is within two weeks (longer
intervals have been reported)
 The incidence is between 15-30%
 It is hoped that as imaging techniques
improve the incidence will decrease
Splenosis

Is the auto transplantation of splenic tissue
after splenic trauma
 They vary from a few millimeters to several
centimeters in diameter
 May occur anywhere in the peritoneal cavity
 Seldom causes symptoms and is usually
discovered as an incidental finding at
reoperation
 Post splenectomy sepsis has renewed
interest in splenosis
Causes of splenomegaly

Infection
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Hematologic processes
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Malignant: Leukemia, lymphoma, histiocytoses, metastatic tumors
Benign: Hemagioma, hamartoma
Metabolic diseases

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Hemolytic anemia: Congenital, acquired
Extramedullary hematopoiesis: thalassemia, osteopetrosis, myelofibrosis
Neoplasms

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Bacterial: Typhoid fever, endocarditis, septicemia, abscess
Viral:E-B virus, CMV, and others
Protozoal: Malaria, toxoplasmosis
Lipidosis: Niemann-Pick, Gaucher disease
Mucopolysaccharidosis infiltration: Histiocytosis
Congestion
Cirrhosis
Cysts
Miscellaneous
Hypersplenism

Refers to a variety of ill effects resulting from
increased splenic function that may be
improved by splenectomy
 The criteria for diagnosis included:
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Anemia, leukopenia, thrombocytopenia or a
combination of the three
Compensatory bone marrow hyperplasia
Splenomegaly
Hypersplenism can be categorized as primary
or secondary
Splenic Involvement in Hodgkin’s
lymphoma

The probability of splenic involvement
increases with increasing spleen size
 The absence of splenomegaly does not
exclude splenic involvement
 Upon gross examination of the spleen a
grayish white nodule ranging from several
millimeters to several centimeters is apparent
with Hodgkin’s disease
 Liver involvement with Hodgkin’s disease
rarely occurs in the absence of splenic
disease
Felty’s Syndrome

Is a syndrome consisting of severe
rheumatoid arthritis, granulocytopenia and
splenomegaly
 It usually occurs in patients with a long history
of rheumatoid arthritis
 Severe, persistent and recurrent infections
are characteristic
 Moderate splenomegaly is common
 Splenectomy is effective in most patients
Gaucher’s Disease

Is a disorder of lipid metabolism that may
result in massive splenomegaly and
hypersplenism
 Commonly found in the Jewish population
 Diagnosis is made by finding the typical
Gaucher’s cells in biopsy tissue
 Massive splenomegaly is usually the most
common form of presentation
 The adult form is the most common form
 Splenomegaly (subtotal) shows great benefits
Cysts and Tumors of the
Spleen

The differential diagnosis of splenomegaly
should include splenic masses and primary
tumors (these conditions are rare however
they must be considered)

Cystic lesions comprise parasitic and nonparasitic
cysts
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Parasitic cysts are due almost exclusively to
echinococcal disease (rare in the United States)
Nonparasitic cysts are classified as primary (true) which
have an epithelial lining or pseudocysts (more common
Symptoms of splenic cysts are vague and are
caused primarily by mass effect (compression of
adjacent viscera)
Cysts and Tumors of the
Spleen
 Selected
nonparasitic cyst may be
managed by aspiration
 Splenectomy should be performed for all
large cyst and those with an uncertain
diagnosis
 Malignant and benign primary tumors of
the spleen are rare
 Most primary malignant tumors are
angiosarcomas
Infectious Mononucleosis

A disease characterized by fever, sore throat,
lymphadenopathy and atypical lymphocytes
 Most patients are young
 Clinical symptoms are similar to those of a
severe upper respiratory tract infection
 The spleen is enlarged and palpable in over
50% of patients
 Splenic rupture may occur
Incidental Splenectomy
 The
spleen is vulnerable to injury during
operative procedures in the upper
abdomen
 When
the splenic capsule is torn,
splenectomy is frequently performed
 Morbidity and mortality is higher with
iatrogenic injury requiring splenectomy
Splenectomy
 Prior
to removing the spleen specific
preoperative preparation is necessary
 All
patients should receive polyvalent
pneumococcal vaccine, polyvalent
meningococcal vaccine and Haemophilus
influenzae type b conjugant vaccine
 Blood and blood products should be
available well in advance of surgery
Blood Compositional Changes
in the Asplenic or Hyposplenic
Patient

The absence of functional splenic tissue
results in characteristic changes in the
circulating blood
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Some of these are predictable and desirable
results
These changes are considered a measure of its
success when splenectomy is performed for a
hematologic disease
Howell-Jolly bodies (nuclear remnants) and
thrombocytosis (desired result)

Other findings include: target cells, acanthocytes (spur
cells), Heinz bodies (denatured hemoglobin) and stippled
red cells
Postsplenectomy Sepsis

Asplenic patients have an increased
susceptibility to the development of
overwhelming infection
 The risk of sepsis is approximately 60 times
greater than normal after splenectomy
 The risk is greatest in children younger than
four years of age
 The risk of sepsis is higher among patients
requiring splenectomy for inherited diseases
 The risk of sepsis after splenectomy is lowest
after trauma
Postsplenectomy Sepsis

Postsplenectomy sepsis syndrome typically
occurs in a previously healthy individual after
a mild upper respiratory tract infection
associated with fever
 Within hours, nausea, vomiting, headache,
confusion, shock and coma can occur; death
follows within 24 hours
 The nature of the syndrome makes it difficult
to diagnose early enough for therapy to be
effective
Postsplenectomy Sepsis

The most common bacteria isolated our
streptococcus pneumoniae, Neisseria
meningitidis, E. coli or Haemophilus
influenzae
 Because half of the patients develop sepsis
from strep pneumoniae, penicillin can be
administered immediately with onset of a
febrile URI
 Patients are instructed to obtain and wear a
Medic alert tag
Hyposplenism

Is a potentially lethal syndrome characterized
by diminished splenic function
 The patient peripheral blood smears appear
as if they are asplenic
 Hyposplenism can occur in the presence of
abnormal sized or enlarged spleen
 The danger of hyposplenism is the risk of
developing potentially lethal sepsis
 Sickle cell anemia is the most common
disease associated with hyposplenism
 The most common surgical disease
associated with hyposplenism is chronic UC
Hyposplenism
Overview
 Definition
of Hyposplenism
 Medical History
 The function of the spleen
 Congenital asplenia vs. splenectomy
 Immunological consequences of
Hyposplenism
 Diagnosis and complications
What is Hyposplenism?
 Hyposplenism
is the lack of a spleen or
its function
 The rare genetic disorder- Congenital
Asplenia
 The surgical removal of the spleensplenectomy
 Results in severe immunological
consequences.
History
 Immunological
 Morris
 First
importance of the spleen
and Bullock-1919
post-splenectomy infection
 O’Donnell-1929
 Effects
 King
of Hyposplenism
and Shumacker-1952
The Spleen
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Largest lymphoid tissue of the body
Serves two main functions
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Filters blood to remove damaged/old RBC- red pulp
Serves as secondary lymphoid tissue by removing infectious
agents and using them to activate lymphocytes- white pulp
A significant reservoir for T lymphocytes
Plays an active role in the production of IgM
antibodies and complement
Has significant role in the functional maturation of
antibodies
Congenital Asplenia
 Autosomal
recessive genetic disorder
 Believed to be caused by absence of
the Hox 11 gene in the embryo
 Causes decreased adaptive immune
response
 Associated with structural abnormalities
in other organs of the body- cause
death in infancy
Splenectomy
 Removal
of spleen tissue (partial or
complete)
 Usually needed because of trauma
 Residual splenic function in ¼ to ⅔ of
patients
 IgM levels decreases, IgG levels remain
constant or increase, IgA and IgE levels
increase
Immunological Consequences
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Causes slower and incomplete adaptive immune
response against bacteria
Low levels of tuftsin, which stimulates phagocytosis
by neutrophils, macrophages, and monocytes
Decreased neutrophil and macrophage activity
Increased NK cell activity
Limited capacity of circulating B-cells to differentiate
into antibody-secreting cells
Decreased level of T-cells
Diagnosis

Determined by anatomic presence or
absence of the organ, its size, and any
lesions.
 Function can be assessed by
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Radiologic Techniques
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X-ray, ultrasound, tomography, MRI, radionucleotide
scanning
Morphologically
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Peripheral blood smear- presence of Howell-Jolly bodies
Howell Jolly bodies
Howell-Jolly
bodies are
round, purple
staining nuclear
fragments of
DNA in the red
blood cell
Complications

Lifelong risk for Overwhelming Postsplenectomy
infection (OPSI)
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Caused by Streptococcus pneumoniae and gram negative
bacteria
Initial Symptoms: fever, chills, muscle aches, headache,
vomiting, diarrhea, and abdominal pain
Progressive symptoms: bacteremic septic shock, extremity
gangrene, convulsions, and coma
Mortality rate of 50-80%


from onset of initial symptoms, 68% of those deaths occur
within 24 hours and 80% occur within 48 hours
Prevention: routine vaccinations and prophylactic antibiotics
Summary

Hyposplenism is the lack of a spleen or its
function
 Can be either genetic or surgically induced
 It has detrimental effects on the immune
system by decreasing the body’s ability to
fight bacterial infections and reducing the
adaptive immune response
Infections in Asplenic Patients
Causes of Asplenia
 Congenital

Often associated with serious organ
malformations
 Acquired
Post surgical removal
 Functional hyposplenism

Function of the Spleen
 Immunological
functions
Main site of opsonic antibody production
 Especially efficient in removal of encapsulated
bacteria
 Remaining RES may compensate but not in
case of encapsulated bacteria

 Filtration
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Removal of abnormal erythrocytes and
intraerythrocytic inclusions eg nuclear
inclusions and parasitised RBC
Overwhelming Infection

Overall incidence of sepsis is low
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3,2% in adults
3,3% in children
Risk stratified according to cause, being highest in
patients with thalassaemia major and sickle-cell anaemia
(J Infect 2001 Oct;43: 182-6)
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Lifetime risk for OPSI of 5%
Mortality

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Death rates 600 times greater than general population
Higher in children (1,7% vs 1,3%), but other reports say
higher in > 16 years
Mandel say doesn’t correspond to indication but Bisharat
et al suggest higher in haematological disorders
Duration of risk
 Most
occur within 2 years post
splenectomy
 Risk is lifelong as cases have been
reported up to 20 years post surgery
 Early complications may be
underreported as surgical complication
Microbiology
 S.
pneumonia
50 – 90% of cases
 Common in all age groups
 Distribution of serotypes seems to be same as
other forms of pneumococcal infection
 75% belonged to serotypes covered in 23
valent vaccine (ibid)

Micro cont…
 H.
influenza
Regarded as 2nd most common cause
 Incidence reduced with vaccination
 Non-typable strains do not seem to
predominate in PSS

 N.
meningitidis

Reported by some studies as associated but
others as well as animal experiments seem to
support a lack of association
Other Micro-organisms

Listeria monocytogenes
 E. coli
 Klebsiella sp
 Salmonella typhimurium
 S. aureus
 Cytocapnophagia canimorsus
 Plesiomonas shigelloides
 Recently occupational exposures have been
highlighted
Management
 Immunisations
Pneumococcal – 2 weeks prior to elective
surgery otherwise when patient is recovered
prior to discharge. Boosters every 5-10 years
 H. influenza – recommended but evidence for
immunogenicity and boosters lacking
 Meningococcal – not routinely recommended
 Influenza – may be of value especially in
reducing risk of secondary bacterial infection

Mx continued…
 Antibiotic
prophylaxis
Controversial
 Penicillin
 In all cases, esp in first 2 years post surgery
 All up to 16 and if underlying immune
dysfunction
 May not prevent sepsis
 Local resistence patterns need to accounted for
 Home antibiotic supply

Cont………
 Travellers
MALARIA PROPHYLAXIS
 Meningococcal vaccine
 Antibiotic prophylaxis

 Education
 Medic
alert bracelet etc.