AB027. SOH25_AB_346. A case report of a bladder tumour in a paediatric patient in Cork University Hospital

Background: Bladder carcinoma predominantly occurs in older adults and is uncommon in children, with an incidence of only 0.1–0.4% in the first two decades of life. In younger patients, it often presents with painless hematuria, which can complicate the diagnostic process. We report on a patient who was 14 years old with a background history of Down syndrome, non-verbal, arthritis, epilepsy, unilateral hearing loss, septal defect repair at age of 1 year. The patient presented with visible haematuria. An ultrasound showed a 3 cm bladder tumour.

Methods: Under general anaesthesia, the patient underwent transurethral resection of bladder tumour (TURBT). A 13 French resectoscope was used. A 3 cm papillary lesion was identified on the left lateral wall of the bladder. Resection was performed and bladder tumour base biopsy was taken. Specimens were sent for histology assessment. Cystodiathermy was performed for haemostasis.

Results: The cytological features of the lesion favoured an inverted urothelial papilloma. However, it was difficult to completely exclude the possibility of an inverted papillary urothelial neoplasm of low malignant potential (PUNLMP) which is the main differential diagnosis. Both lesions can recur if incompletely resected and therefore check cystoscopy recommended. In this patient there was an association with a FGFR-3 gain of function fusion (and specifically the lack of RAS mutations), the current literature supports classification as an inverted PUNLMP.

Conclusions: Bladder carcinoma is rare in children, often presenting with diagnostic challenges. This case highlights a 14-year-old with Down syndrome presenting with hematuria and a bladder tumor. Histology revealed features of an inverted urothelial papilloma, though molecular analysis supported classification as PUNLMP. Complete resection and surveillance are critical to managing recurrence risk.

Keywords: Bladder tumour; visible haematuria; urothelial papilloma; papillary urothelial neoplasm of low malignant potential (PUNLMP); bladder tumour in paediatric