Squamous Dysplasia of the Urinary Bladder

Squamous dysplasia of the urinary bladder is uncommon and may represent a precursor to invasive squamous cell carcinoma. Though significant focus has been devoted to squamous differentiation in invasive bladder cancer, relatively little attention has been given to squamous dysplasia. We methodically reviewed microscopic slides from a consecutive cystectomy series at our institution (n = 303; 2001-2014), with special attention given to squamous dysplasia and squamous differentiation within association invasive carcinoma. Of these 303 cases, 3% (9 cases) had squamous dysplasia. The majority (89%; 8/9) had a similar morphological appearance to squamous dysplasia of the head and neck (ie, cytological atypia, architectural disturbances, and abnormal keratinization). Invasive carcinoma was present in 230 of the cystectomy cases. Of these 230 cases with invasive carcinoma, 4% (8 cases) also had squamous dysplasia. The invasive carcinoma had evidence of squamous differentiation in all cases with concurrent squamous dysplasia. Concurrent flat urothelial carcinoma in situ was present in 3 of the 8 cases with both invasive carcinoma and squamous dysplasia. Squamous dysplasia was not associated with clinical outcomes data, including death from bladder cancer and bladder cancer recurrence. The data from this study indicate that squamous dysplasia is uncommon in the cystectomy setting, frequently has the morphology of head and neck dysplasia, and is often associated with invasive carcinoma with squamous differentiation.