Clinical History
73-year-old male patient hospitalised complaining of severe lumbar pain and dysuria.
Past medical history including radical prostatectomy plus adjuvant radiotherapy for prostate cancer 11 years earlier, right nephro-ureterectomy for transitional cell carcinoma 3 years earlier.
Recent scintigraphic diagnosis of skeletal metastases mainly involving the dorso-lumbar spine (normal serum PSA level).
Imaging Findings
The postoperative urinary apparatus was evaluated using MDCT urography, without signs of recurrence after right nephrectomy. The left kidney showed normal parenchymal enhancement, opacified nondilated collecting systems and ureter.
Circumferential wall thickening of the urinary bladder was detected, more pronounced on its right side, with perceptible contrast enhancement during the venous phase. In the excretory acquisition, the moderately distended bladder appeared opacified, with diffusely irregular lumen contour without appreciable vegetations.
Ultrasound examination during instillation of saline through Foley catheter demonstrated sufficient distensibility of the bladder, without appreciable masses.
Pelvic MRI, performed to investigate bladder thickening suspicious for neoplasia and guide endoscopic biopsy, confirmed moderately distended bladder with circumferential wall thickening showing diffuse T2-hypointense signal consistent with fibrotic content, without appreciable hyperintense pathologic tissue, homogeneously enhancing after Gadolinium administration.
Cystoscopy and random biopsies failed to detect neoplastic changes leading to a diagnosis of radiation cystitis.
Discussion
Cystitis is a possible complication following external, interstitial or intracavitary radiation therapy of pelvic neoplasms [1, 2]. Its acute form presents with haematuria 4-6 weeks after therapy, may last up to 4 months, is usually self-limiting and conservatively treated.
Conversely, chronic radiation cystits usually manifests 1 to 4 years after radiation, but longer intervals of 10 or more years are not uncommon. Its symptoms are related to the contracted bladder. Treatment includes hyperbaric oxygen administration and intravesical instillation of aluminium, formaline or silver nitrate; urinary diversion by percutaneous nephrostomy or cystectomy is the last option [3].
At pathology, submucosal mixed acute and chronic inflammatory cell infiltrate is invariably present; surface ulceration is common in early stages, whereas in the chronic phase interstitial fibrosis predominates, following ischaemia due to obliterative endoarteritis [2, 4].
At imaging, radiation cystitis appears as a small-volume bladder with circumferentially thickened wall, possible calcifications and associated hydronephrosis. Mural thickening can be asymmetric, sometimes with contrast enhancement consistent with inflammation [2, 5].
Currently, MDCT is the primary imaging modality to detect urinary tract abnormalities: bladder epithelial cancer has its enhancement peak in the nephrographic phase and appears hyperdense relative to the low-attenuated urine within the bladder; during excretory phase acquisition, neoplasm are detected as focal or extensive mural thickening against a background of opacified urine [5].
MDCT-urography is accurate in the detection of bladder neoplasms with a very high negative predictive value, but interpretation may be confounded by other infectious, inflammatory and iatrogenic conditions that closely mimic tumour, or obscure superimposed or recurrent cancer. Furthermore, detection of neoplasia in treated bladders can be challenging even at cystoscopy.
As this reported case exemplifies, MRI can be a valuable complementary modality to further investigate CT finding of nonspecific bladder thickening: together with knowledge of the patient’s medical history, differentiation of radiation cystitis from bladder cancer can be suggested by the T2-hypointense signal corresponding to the predominant post-radiation interstitial fibrosis, whereas persistent mural enhancement may be observed even years after treatment.
Differential Diagnosis List
Chronic radiation cystitis
Urinary bladder epithelial cancer
Malacoplakia
Bladder tuberculosis
Schistosomiasis
Detrusor muscle hypertrophy
Final Diagnosis
Chronic radiation cystitis
