3. CASE HISTORY
ďą An 26 yrs old female presented with dull pain right side
of upper abdomen, a dragging sensation over right
hypochondrium and occasional fever nearly one month
⢠Pain not relieved with analgesics
⢠Examination revealed mild hepatomegaly
⢠Routine blood test was normal
⢠Advised for imaging study of abdomen
7. INTRODUCTION
⢠Zoonosis
⢠3 forms of Echinococcosis:
ďCystic echinococcosis (CE): Tropical and subtropical regions;
Echinococcus granulosus (Unilocular cyst)
ďAlveolar echinococcosis (AE): Temperate northern
hemisphere; Echinococcus multilocularis (Multilocular cyst)
ďPolycystic echinococcosis (PE): Latin America; Echinococcus
vogeli & Echinococcus oligarthus
ďź CE eradicated in Iceland, New Zealand and Tasmania.
ďź Definitive host: Dogs and other canines
ďź Intermediate host: Sheep, goat, swine etc
8. GLOBAL DISTRIBUTION
Figure 1. Geographic distribution of hydatid disease. Map shows areas in which hydatid
disease is endemic due to the transmission of E granulosus by means of the dog-sheep
cycle (solid red areas). Red stripes indicate areas where transmission occurs by means of
alternative life cycles in which carnivores such as wolves and foxes serve as definitive
hosts and goats, camels, and horses serve as intermediate hosts. Transmission by means
of alternative life cycles is common in North Africa, the Middle and Far East, the United
States, Canada, and Iceland
10. EPIDEMIOLOGY
ďś Cystic Echinococcosis:
⢠Highly endemic in pastoral communities
⢠Genotypes G1â10; G1 strain of E. granulosus accounts for 95%
of human infections and has a dog-sheep transmission
⢠Incidence rates as high as 50/100 000 person-years
⢠Risk factors: Ownership of livestock (mainly dogs, sheep);
occupation (pastoralism, agriculture);
uncontrolled slaughtering; poor water hygiene
ďś Alveolar Echinococcosis:
⢠Definitive hosts: mainly foxes and domestic dogs
⢠Intermediate hosts: Arvicolid and Cricetid rodents
⢠Prevalence: 0.02% and 1.4%
⢠Global annual incidence 18,235 cases per year
12. PATHOGENESIS
⢠One or more spherical cysts, most frequently in liver & lungs
⢠Tissue damage & organ dysfunction by gradual process of
space occupying compression
⢠Cyst structure:
o Outer pericyst: composed of modified host cells that form a
dense and fibrous protective zone
o Middle laminated membrane: acellular and allows the passage
of nutrient
o Inner germinal layer: forms brood capsule which develops
asexually into protoscolices (the larval stage of the parasite)
from which daughter cysts are produced.
⢠Cysts modulate immune response by Th1 cell activation &
impairment of macrophages
15. CLINICAL FEATURES
⢠Asymptomatic in most cases; incidental finding
⢠Most symptomatic cysts are ⼠5 cm
⢠Pressure effect on liver and biliary tree
⢠Abdominal pain , hepatomegaly, jaundice
⢠Pulmonary cysts: Cough with expectoration, SOB,
chest pain, hemoptysis
⢠Other sites: Pathological #, Brain SOL, Conduction
defects, Pericarditis, Pelvic mass
⢠Leakage of cyst contents or infection of cyst
⢠Pain, flushing and urticaria
⢠Anaphylactic reaction
⢠Fever and sepsis
16. COMPLICATION OF CYSTS
⢠Cysts with fistulas
⢠Biliary/bronchial obstruction (due to spillage of cyst
content via cysto-biliary/cysto-bronchial fistulas)
⢠Bacterial infection
⢠Compression syndromes
ďźBlood vessels (leading to thrombosis, BuddâChiari
syndrome)
ďźBiliary ducts
ďźBronchi
ďźParenchyma/muscles, nerves (leading to atrophy)
⢠Cyst rupture
⢠Venous/arterial embolism
17. OTHER DDx
⢠Neurocysticercosis
⢠Cholangiocarcinoma
⢠Imaging in NonSmall Cell Lung Cancer
⢠Imaging in Small Cell Lung Cancer
⢠Imaging of Benign Breast Calcifications
⢠Lung Metastases Imaging
⢠Metastatic Cancer With Unknown Primary Site
⢠Pancreatic Pseudocyst Imaging
⢠Pyonephrosis
⢠Renal Cancer
⢠Splenic Abscess
18. INVESTIGATIONS
ďą LABORATORY WORK UP:
⢠Routine lab tests: No specific findings
⢠Cyst rupture in biliary tree: marked & transient elevation of
cholestatic enzyme levels , often with hyperamylasemia and
eosinophilia <15% (in 60% cases)
⢠SEROLOGY: Confirmatory role; Indirect hemagglutination test
& ELISA for detection of anti-Echinococcus Antibodies [IgG]
⢠10% hepatic cysts & 40% pulmonary cysts exhibit false
negative results
-ve in CE1/CE2/CE4/CE5; +ve only when endocyst ruptures
⢠Diagnostic puncture & aspiration can be performed for
histological diagnosis
⢠PCR contribute to the differential diagnosis between CE and
AE in doubt.
20. OTHER INVESTIGATIONS
⢠CT scan can detect extrahepatic smaller cysts, differentiating
parasitic from nonparasitic by measurement of cyst density &
for follow up studies during chemotherapy
⢠MRI used in the evaluation of postsurgical residual lesions,
recurrences & cardiac infections. Also superior in identifying
changes of the intrahepatic and extrahepatic venous system &
in identifying cystobiliary fistulas.
⢠Assessment of Parasite Viability:
ďź Histopathology (intact parasite-derived cyst wall including
germinal layer)
ďź Evaluation of the protoscolices (flame cell activity and
morphological integrity; eosin staining)
ďź Metabolic viability assessment using high-field H-MRS of cyst
content
ďź RT-PCR
22. MANAGEMENT
ďś Depends on the size, location and manifestations of cysts
ďś In uncomplicated cysts: âExpert consensus for the diagnosis
and treatment of cystic and alveolar echinococcosis in
humansâ, published by the WHO-Informal Working Group on
Echinococcosis recommends four treatment modalities:
⢠1. Drug treatment with benzimidazoles
⢠2. Percutaneous sterilization techniques
⢠3. Surgery
⢠4. âWatch and waitâ
23.
24. BENZIMIDAZOLES
ď§ Indication:
1. CE 1,2,3a,3b of size 5-6 cm
2. Prevention of secondary CE after interventions or after
spontaneous rupture; starting at least 4 hours before & upto
1 month after intervention
⢠Dosage: Albendazole 10-15 mg/kg/day in 2 divided doses or
Mebendazole 40-50 mg/kg/day in 3 divided doses; with a fat-
rich meal for 3-6 months
⢠Monitoring: Liver enzymes (upto 2-4x) & CBC at day 5, 10,
then at 2 weekly intervals ,later monthly
⢠Contraindications: Pregnancy; cysts at risk of rupture;
hepatoxicity; leucopenia; bone marrow suppression
⢠Follow up: 12 months after treatment completion to look for
re-activation & min of 5 yrs after cysts reached inactive stage
(CE4, CE5)
25. Puncture â Aspiration â Injection â
Re-Aspiration (PAIR)
⢠Indication: CE1 and CE3a cysts of liver of size 5â6 to <10 cm
⢠Principle: Sterilization of the germinal layer and protoscolices.
Only fluid is removed; all other parasitic material remains
⢠Prerequisites: Experienced interventionalist; resuscitation set
up for severe anaphylactic reactions & surgical back-up
26. Puncture â Aspiration â Injection â
Re-Aspiration (PAIR)
⢠Major steps :
1. Prophylaxis of secondary echinococcosis with albendazole
2. Percutaneous puncture of the cyst under US (or CT) guidance
3. Aspiration of cyst fluid
4. Testing for bilirubin (evaluation of aspect of fluid and test strip
result) and injection of contrast medium (verification of absence
of cysto-biliary communications)
5. Aspiration of contrast medium
6. If fistulas are reliably ruled out: injection of protoscolicidal
agent â 95% ethanol or 20% NaCl to remain in the cyst for 10â15
mins
7. Re-aspiration of the fluid
8. Follow-up for a minimum of 5 years to detect relapses and
secondary CE
27. SURGERY
⢠INDICATION:
1. Any cyst >10 cm
irrespective of CE staging
2. Cysts 5-6 to <10 cm in CE 2
and CE 3b
3. Complicated cysts
⢠FOLLOW-UP: minimum of 5
years.
28. SURGERY
1. Partial Cystectomy: Removal
of the parasite-derived cyst
components (endocyst) & part
of the pericyst (host-derived
connective tissue capsule).
2. Total cystectomy and
Resection
a. Total cystectomy: endocyst
and the entire pericyst
b. Resection: additional removal
of part of the organ where CE-
cyst is embedded
29. âWatch and Waitâ
⢠Cyst allowed to
progress along its
natural course if
asymptomatic
⢠Indicated in CE 4 & CE 5
Stages
⢠Follow-up patients with
CE4 and CE5 cysts for a
min of 5 years
30. Management of Complicated
Cyst
ďą Cysto-biliary and cysto-bronchial fistulas: ERCP, if possible,
followed by early surgery under albendazole cover
ďą Bacterial Infection: Initially, abscess management with
drainage and antibiotics followed by specific management of
residual CE cyst/cavity & albendazole therapy
ďą Compression Syndromes: Rapid decompression of blood
vessels, bile ducts, bronchi, parenchyma, muscle, nerves
ďą Cyst Rupture: Allergic Reactions and Secondary CE:
⢠standard approach to allergic reactions including anaphylactic
shock followed by CE-specific treatment
⢠To prevent secondary CE, surgical intervention to clear CE cyst
material and benzimidazole therapy
31. PREVENTION
ďą 4 phases: (1) planning; (2) attack; (3) consolidation; and (4)
maintenance of eradication
ďą Horizontal approaches: Slow-track (>25 yrs)
⢠reduction of disease transmission through primary healthcare
interventions, including health education, general husbandry
improvements, upgrading of abattoirs & meat inspection
⢠regular deworming of dogs by their owners
ďą Vertical or fast-track approach: 3-5 yrs
⢠Mass treatment of dogs, dog registration and reduction of
stray dog numbers
⢠EG95 vaccine 95% effective against ovine hydatidosis
33. INTRODUCTION
ď Organism: Echinococcus multilocularis
ď Global distribution: Temperate northern hemisphere
ď Epidemiology:
⢠Definitive hosts: mainly foxes and domestic dogs
⢠Intermediate hosts: Arvicolid and Cricetid rodents
⢠Prevalence: 0.02% and 1.4%
⢠Global annual incidence: 18,235 cases per year
ď Site of infection:
⢠E. multilocularis metacestode (larva) develops primarily in the
liver.
⢠In advanced stages, other sites may become metastasized
such as retroperitoneum, lungs, brain and bones
34. PATHOLOGY
⢠Conglomerate of scattered vesicles, each ranging from a few
mm to cm in size
⢠Germinal layer represents the proliferating metacestode
generating new vesicles, which leads to the tumour-like
behaviour of the parasite.
⢠A granulomatous host reaction surrounds the metacestode,
including a vigorous synthesis of fibrous and germinative
tissue.
⢠3 immune mediated clinical outcome:
(1) resistance as shown by the presence of âdying outâ or
âabortedâ metacestodes;
(2) controlled susceptibility by a slowly growing metacestode
tissue â presents 5â15 years after infection;
(3) Uncontrolled hyperproliferation of the metacestode due to
an impaired immune response
35. DIAGNOSIS
⢠Serology: Em2, Em2+, Em18 antigens
⢠Imaging: USG/CT/MRI/PET
⢠Diagnostic puncture and aspiration of parasitic material
⢠Histology
⢠RT-PCR
⢠PNM Classification: Resemblance to malignant diseases
P primary mass in the liver
N involvement of neighbouring organs (lymph nodes)
M metastases
36. MANAGEMENT
⢠Curative treatment is possible with combination of radical
surgery with 2 cm liver margin & subsequent drug treatment
(benzimidazoles) for at least 2 years.
⢠Life long follow up
⢠Recurrences have been observed almost 20 years after
surgery
⢠After successful surgery, anti-Em18 or anti-Em2+ antibodies
decline rapidly, and seroconversion to undetectable levels
correlates well with curative resection
⢠Advanced stage lesions: life long benzimidazole therapy &
management of acute problems such as obstruction of bile
ducts, abscess formation and thrombosis of major blood
vessels
⢠Liver transplantation