Bladder & ureters
Cystitis
Schistosomiasis (bilharziasis)


Topic Completed: 25 July 2019

Revised: 25 July 2019

Copyright: 2003-2019, PathologyOutlines.com, Inc.

PubMed Search: Schistosomiasis[TI] bladder[TI] full text[sb]

See Also: Parasitology chapter

Y. Albert Yeh, M.D., Ph.D.
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Cite this page: Yeh YA. Schistosomiasis (bilharziasis). PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/bladderschistosomiasis.html. Accessed December 7th, 2019.
Definition / general
  • Parasitic infection of the bladder with blood flukes (trematodes), Schistosoma species (mainly Schistosoma haematobium)
Essential features
  • Bladder schistosomiasis is most commonly caused by Schistosoma haematobium
  • Eggs of Schistosoma haematobium: 110 - 170 μm, oval with terminal spine
  • Eggs of Schistosoma mansoni: 115 - 175 μm, oval with lateral spine
  • Few case reports of bladder schistosomiasis caused by Schistosoma mansoni and Schistosoma haematobium - Schistosoma mansoni hybrid (Emerg Infect Dis 2019;25:365)
  • Coinfection with Schistosoma haematobium and Schistosoma mansoni occurs (East Afr Med J 2013;90:36)
Terminology
  • Bladder bilharziasis is named after Theodor Bilharz, a German physician who discovered the first blood fluke causing urinary schistosomiasis in 1851 (Wikipedia: Schistosomiasis [Accessed 6 May 2019])
  • Bladder schistosomiasis
  • Genitourinary schistosomiasis
  • Schistosomiasis related cystitis
ICD coding
Epidemiology
Pathophysiology
  • After penetration of skin or mucous membranes, schistosomulae migrate through the lungs to portal venous system and mature into adults
  • About 6 weeks later, adult worms migrate to bladder venules (Nat Rev Dis Primers 2018;4:13)
  • Females lay eggs that reach the bladder wall, penetrate bladder mucosa and excrete into urine
  • Bladder wall shows eggs with mixed inflammatory reaction with lymphocytic, neutrophilic and eosinophilic infiltrate and scarring of the vesicular vessels
  • Parasitic eggs provoked chronic granulomatous inflammation with calcifications and fibrotic thickening of the bladder wall, deposits of calcified eggs in later stage (Nat Rev Dis Primers 2018;4:13)
  • Eggs may block drainage of urine into the bladder, causing hydroureter
  • May develop secondary bacterial urinary tract infections, renal failure and pulmonary hypertension (Hum Pathol 1986;17:333)
  • May progress to bladder cancer (squamous cell carcinoma [80 - 85%], adenocarcinoma [5 - 15%] and rarely urothelial carcinoma) (Front Med (Lausanne) 2018;5:223)
Etiology
  • Humans infected with schistosomes after exposure to cercariae released by snails (Bulinus species) in fresh water
  • Penetration of skin or mucous membranes by cercariae (survives 3 - 4 days in fresh water)
  • Schistomulae migrate to bladder plexus and nearby veins and venules (Nat Rev Dis Primers 2018;4:13)
  • Female schistomulae deposit their eggs
  • Some eggs reach the bladder wall, penetrate bladder mucosa and excrete in urine
  • Eggs hatch and release miracidia
  • Miracidia penetrate snail intermediate hosts (Bulinus species)
  • After 2 generations of sporocysts, the snails produce cercariae and release them in fresh water (CDC: Parasites - Schistosomiasis [Accessed 8 May 2019])
Diagrams / tables

Images hosted on other servers:

Life cycle

Clinical features
  • Swimmer's itch: cercarial dermatitis (days after infection)
    • Local erythema, pruritic maculopapular rash
  • Acute schistosomiasis (2 - 8 weeks after infection) (Lancet Infect Dis 2007;7:218)
    • Katayama syndrome: fever ("snail fever"), cough, muscle pain, malaise, abdominal pain
    • Hematuria, dysuria, suprapubic pain, urinary tract infections
  • Chronic schistosomiasis (within months after infection)
Diagnosis
  • Detection of Schistosoma haematobium or Schistosoma mansoni eggs in urine samples or bladder tissues (J Egypt Soc Parasitol 2017;47:211)
  • Schistosoma haematobium eggs: 110 - 170 μm × 40 - 70 μm, oval with terminal spine (Hum Pathol 1986;17:333)
  • Schistosoma mansoni eggs: 115 - 175 μm × 45 - 47 μm, oval with lateral spine
Laboratory
Radiology description
  • For bladder schistosomiasis: bladder wall thickening (usually > 4 mm) on ultrasound
  • For carcinoma arising in bladder schistosomiasis: focal bladder wall thickening or mass on ultrasound
Prognostic factors
  • Good prognosis for patients with early disease
  • Prognosis is worse for chronic infections with complications:
    • Immune complex glomerulonephritis
    • Obstructive nephropathy
    • Obstructive uropathy
    • Chronic pyelonephritis
    • Amyloidosis
    • Bladder cancer (risk 1.72, further increased in smokers)
  • References: J Adv Res 2013;4:453, Nat Rev Dis Primers 2018;4:13
Case reports
Treatment
  • Single course of praziquantel treatment can be curative
  • Corticosteroids (severe disease), metrifonate (alternative therapy) for bladder schistosomiasis (ChemMedChem 2018;13:2374)
Clinical images

Images hosted on other servers:
Missing Image

Schistosoma haematobium fluke

Missing Image

Adult (female and male)

Gross description
  • Early active stage: erythematous, sessile or pedunculated polyps, "grainy sandy" patches (Urology 2017;107:e7)
  • Chronic stage: fibrotic thickening of bladder wall, stellate ulcers, tumor-like lesions (Hum Pathol 1986;17:333)
Gross images

Images hosted on other servers:
Missing Image

Related squamous cell carcinoma

Microscopic (histologic) description
Microscopic (histologic) images

Contributed by Y. Albert Yeh, M.D., Ph.D.

Calcified eggs and keratin

Schistosoma eggs and keratin

Schistosoma eggs with terminal spine

Bladder calcified eggs

Calcified eggs with cracks

Parasitic calcified eggs


Dysplastic keratinizing squamous cells

Malignant squamous cells

Malignant squamous cells with intercellular bridges



Contributed by Drs. Kiran Alam, Anshu Jain, Veena Maheshwari, Farhan A. Siddiqui and Ershadul Haq

Schistosoma eggs in ureter

Ureter with Schistosoma eggs

Muscularis propria with Schistosoma eggs

Schistosoma eggs

Cytology description
  • Uncommon in urine but if present, may show an oval calcified egg with a lateral or terminal spine
Cytology images

Contributed by Y. Albert Yeh, M.D., Ph.D.

Calcified eggs in urine

Schistosoma egg with lateral spine

Positive stains
Negative stains
  • Schistosoma haematobium egg shells: acid fast
Molecular / cytogenetics description
  • Common chromosomal aberrations in schistosomiasis associated bladder cancer (Carcinogenesis 2000;21:1721)
    • Loss: 8p, 18q, 17p, 5q, 9p, 10q, 11q, 18p, 11p, 9q, 20p, 6q (in descending order)
    • Gain: 17q, 5p, 7q, 7p, 1q (in descending order)
  • Most common genetic alterations in schistosomiasis associated bladder cancer (Nat Clin Pract Urol 2005;2:502)
    • Low grade urothelial carcinoma: chromosome 9 loss of heterozygosity, FGFR3 activating mutation
    • Dysplasia and carcinoma in situ: TP53 mutations, chromosome 9 loss of heterozygosity
  • Loss of heterozygosity in schistosomiasis associated bladder cancer versus non schistosomiasis associated bladder cancer (J Natl Cancer Inst 1995;87:1383)
    • 9p loss of heterozygosity (twofold higher in schistosomiasis associated bladder cancer)
    • 9q loss of heterozygosity (threefold lower in schistosomiasis associated bladder cancer)
  • Genes involved in schistosomiasis associated bladder cancer (Clin Microbiol Rev 1999;12:97)
    • Mutation of FGFR3 (> 30%, more frequent in low grade papillary tumors)
    • Activation of HRAS (7 - 17%, more frequent in low grade papillary tumors)
    • Homozygous deletions of p16INK4A (more common in high grade Ta tumors) (Am J Pathol 1999;155:105)
    • Inactivation of tumor suppressor genes TP53 and RB (more common in carcinoma in situ and high grade invasive tumors)
    • Overexpression of ERBB2 in advanced urothelial carcinoma
    • BCL2 expression in later stages of squamous cell carcinoma
Sample pathology report
  • Urinary bladder, dome, biopsy:
    • Urothelial mucosa with ulcerations, chronic granulomatous inflammation with eosinophils and calcified parasitic eggs, consistent with schistosomiasis related cystitis
    • Comment: The urothelial mucosa shows urothelial mucosa with granulation tissue and mixed inflammatory infiltrate composed predominantly of lymphocytes, neutrophils and eosinophils. There are many calcified oval parasitic eggs measuring approximately 120 microns with a sharp terminal spine. These changes of cystitis are consistent with Schistosoma haematobium infection. A small fragment of the muscularis propria is also present in the biopsy specimen.
Differential diagnosis
Board review question #1
What is the most common pathogen of bladder schistosomiasis?



  1. Schistosoma haematobium
  2. Schistosoma haematobium - Schistosoma mansoni hybrid
  3. Schistosoma intercalatum
  4. Schistosoma japonicum
  5. Schistosoma mansoni
Board review answer #1
A. Schistosoma haematobium

Reference: Schistosomiasis (bilharziasis)

Comment Here
Board review question #2
Which of the following parasitic eggs contains a terminal spine?

  1. Schistosoma haematobium
  2. Schistosoma japonicum
  3. Schistosoma mansoni
  4. Schistosoma mekongi
Board review answer #2
A. Schistosoma haematobium

Reference: Schistosomiasis (bilharziasis)

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