View source for WBR0677

 {{WBRQuestion
|QuestionAuthor= {{YD}} (Reviewed by Serge Korjian)
|ExamType=USMLE Step 1
|MainCategory=Pathology
|SubCategory=Genitourinary
|MainCategory=Pathology
|SubCategory=Genitourinary
|MainCategory=Pathology
|SubCategory=Genitourinary
|MainCategory=Pathology
|MainCategory=Pathology
|MainCategory=Pathology
|SubCategory=Genitourinary
|MainCategory=Pathology
|SubCategory=Genitourinary
|MainCategory=Pathology
|SubCategory=Genitourinary
|MainCategory=Pathology
|SubCategory=Genitourinary
|MainCategory=Pathology
|MainCategory=Pathology
|SubCategory=Genitourinary
|Prompt=A 60-year-old Egyptian man presents to the physician's office complaining of painless hematuria. Following appropriate work-up, the diagnosis of squamous cell carcinoma of the bladder is made. The physician explains to the patient that his condition is associated with an infectious agent. Which of the following is most likely the primary mechanism that led to the patient's cancer?
|Explanation=Squamous cell carcinoma (SCC) of the bladder is caused by chronic granulomatous inflammation of the bladder that eventually leads to metaplasia of the transitional epithelium and then progresses to neoplasia. SCC of the bladder is strongly associated with Schistosoma haematobium, a parasite commonly found in the the Middle East region and especially in Egypt. At first, the adult parasite invades the bladder venous plexus and then the urinary bladder itself. It releases eggs that cause irritation and subsequent chronic granulomatous inflammation in the mucosa and the submucosa.
|AnswerA=Chronic granulomatous inflammation
|AnswerAExp=Chronic granulomatous inflammation (chronic cystitis) is the primary etiology behind squamous cell carcinoma of the bladder due to S. haematobium
|AnswerB=Free radical injury
|AnswerBExp=Free radical injury is not the primary etiology behind squamous cell carcinoma of the bladder.
|AnswerC=Mutation of p53 tumor suppressor gene
|AnswerCExp=p53 mutation is not the primary etiology behind squamous cell carcinoma of the bladder. p53 mutations are at the root of neoplastic transformation in colon cancer, 
|AnswerD=Mutation of mismatch repair gene
|AnswerDExp=Mismatch repair gene mutation is not the primary etiology behind squamous cell carcinoma of the bladder.
|AnswerE=Carcinogenic parasitic components incorporated within host DNA
|AnswerEExp=Carcinogenic bacterial components incorporated within DNA is not the primary etiology behind squamous cell carcinoma of the bladder.
|EducationalObjectives=S. haematobium releases eggs in the bladder that cause irritation and chronic granulomatous inflammation. Eventually, the transitional epithelial wall of the bladder undergoes metaplasia to squamous cell before it finally transforms into neoplasia.
|References=Rambau PF, Chalya PL, Jackson K. Schistosomiasis and urinary bladder cancer in North Western Tanzania: a retrospective review of 185 patients. Infectious Agents and Cancer. 2013;8:19
|RightAnswer=A
|WBRKeyword=Chronic granulomatous inflammation, Schistosoma haematobium, Squamous cell carcinoma, Bladder cancer
|Approved=Yes
}}