Keratinising Desquamative Squamous Metaplasia (KDSM) of the bladder is a rare histopathological condition characterized by the replacement of urothelial cells with keratinized squamous epithelium (1). KDSM presents with nonspecific symptoms, including hematuria and dysuria, and can mimic other bladder pathologies such as bladder carcinoma (2). Currently, there is no standardized approach for managing KDSM due to its rare presentation and variable clinical course. This systematic review aims to evaluate current diagnostic and therapeutic strategies, as well as long-term outcomes, for patients diagnosed with KDSM in the bladder. It also aims to suggest evidence-based recommendations for clinical practice.

A comprehensive literature search was conducted using PubMed, Scopus, and the Cochrane Library to identify relevant studies published between 1990 and 2022. Studies were included if they reported on patients with histologically confirmed KDSM of the bladder, detailed the management strategies employed, and provided follow-up data on long-term outcomes. Data extracted from eligible studies included patient demographics, presenting symptoms, diagnostic approaches, treatment modalities, recurrence rates, and any reported complications.

The most common presenting symptoms were haematuria, dysuria and urinary frequency (3). Cystoscopy was the primary diagnostic method, with biopsy confirming KDSM in all cases. Conservative management, focusing on addressing underlying causes such as chronic urinary tract infections or bladder stones, was utilized in 75% of cases. Surgical interventions, including resection of keratinized tissue, were reported in some studies. Recurrence rates varied between 9-13% in the included studies, with most recurrences successfully managed with additional conservative therapy. In a small number of cases, progression to squamous cell carcinoma was reported. Overall, the long-term prognosis was favourable for most patients, though surveillance is crucial due to the potential for recurrence and malignant transformation in rare cases (1).

The management of KDSM remains variable, with no universally accepted treatment protocols. Conservative management, particularly addressing underlying irritants such as chronic infections or long term catheterization, appears to be effective in the majority of cases. Surgical resection is reserved for symptomatic or recurrent cases. However, the risk of recurrence and the potential for malignant transformation necessitate ongoing surveillance, particularly in patients with a history of chronic irritation or those who require invasive treatments. This review emphasizes the need for early diagnosis and individualized treatment plans based on the severity of symptoms and the presence of underlying causes.

KDSM of the bladder is a rare condition that requires a high level of clinical suspicion for diagnosis. Conservative management, addressing the underlying causes of bladder irritation, is effective in most cases. Surgical intervention is warranted in recurrent or symptomatic cases, but long-term follow-up is essential to monitor for recurrence and potential progression to squamous cell carcinoma. Further prospective studies are needed to establish more definitive management guidelines and to better understand the long-term clinical course of KDSM in the bladder.

Ganeshappa, A., Krambeck, A., Grignon, D. and Lingeman, J., 2009. Endoscopic management of keratinizing desquamative squamous metaplasia of the upper urinary tract: a case report and review of the literature. Journal of Endourology, 23(9), pp.1513–1517.
Borofsky, M., Shah, R. and Wolf, J.S. Jr., 2009. Nephron-sparing diagnosis and management of renal keratinizing desquamative squamous metaplasia. Journal of Endourology, 23(9), pp.1519–1523.
Al-Marhoon, M.S., Saparamadu, P.A.M., Venkiteswaran, K.P., Shareef, O. and Mathewkunju, J., 2013. Squamous cell carcinoma arising in keratinizing desquamative squamous metaplasia of the renal pelvis. Sultan Qaboos University Medical Journal, 13(3), pp.466–469.