Keratinizing squamous metaplasia is considered a pre-malignant condition with a reported incidence of 23% in patients with SCI who use indwelling catheters for bladder management (1
). In patients diagnosed with keratinizing squamous metaplasia, the subsequent risk of developing bladder cancer has been estimated to be 21% to 32% (1
). Khan et al (1
) reviewed 34 patients with histologically proven keratinizing squamous metaplasia and postulated that some cases with synchronous or metachronous bladder cancer progress to carcinoma in situ and ultimately invasive tumor. Likewise, Guo et al (4
) recently described findings of 5 patients diagnosed with keratinizing squamous metaplasia. Two of 5 (40%) were found to have invasive squamous cell carcinoma identified on cystectomy performed within 1 year of the initial diagnosis, and an additional 1 of 5 (20%) had persistent keratinizing squamous metaplasia on repeat bladder biopsy.
Although the exact pathophysiology underlying the transformation from keratinizing squamous metaplasia to squamous cell carcinoma is unknown, several etiologic factors have been linked its development (1
). Chronic inflammation caused by indwelling catheters and stones, as well as infection secondary to parasites, are considered to be the most likely etiologic agents (1
). Histopathologically, Guo et al (4
) recently reported enhanced activity of epithelial growth factor receptor (EGFR) in keratinizing squamous metaplasia after cystectomy in patients with hematuria, as well as patients with urinary retention. EGFR is a tyrosine kinase that transduces signals controlling cell proliferation. Stonehill et al (2
) reviewed 208 charts of patients with SCI with neurogenic bladder and chronic indwelling catheters and concluded that nearly all patients had inflammatory changes or squamous metaplasia of the bladder, whereas 1 patient had keratinizing squamous metaplasia.
Because of this increased risk, many centers recommend frequent surveillance to diagnosis lesions at a curable phase (2
). For patients with SCI who have been managed with indwelling urinary catheters for less than 5 years and found to have limited keratinizing lesions, several investigators recommend annual cystoscopy and urinary cytology (1
). For patients with SCI managed with indwelling urinary catheters for greater than 10 years with more extensive keratinizing lesions, attempts at reductive therapy with cauterization or silver nitrate fulguration are recommended (1
). However, because of limited data on these types of protocols, no approach can be considered superior (1
), and some have been proven ineffective (1
). Most recently, some authors have suggested that EGFR could potentially be used as logic therapeutic target for keratinizing squamous metaplasia, among other bladder lesions, that are difficult to manage clinically (4
). However, some investigators advocate for a more aggressive management with radical bladder resection to avoid development of malignant transformation (1
Patients with SCI may experience significant difficulty adjusting to life-altering events including radical surgery (16–20
). The psychologic and quality-of-life impact of prophylactic radical cystectomy in patients with keratinizing squamous metaplasia is unknown; however, performance of a radical cystectomy may affect many quality-of-life issues including stoma care, catheter use, and presence of incontinence, body image, and sexual dysfunction (21–25
). Because of these significant concerns, we recommend that a team be formed including SCI specialists, urologists, nurses, social workers, psychologists, and family members to construct an individualized treatment for each affected patient.