Transitional cell carcinoma (TCC) of the upper urinary tract is associated with significant morbidity and mortality and is an important genitourinary cancer. Squamous differentiation is a common histological variant in lower tract TCC, however is rare in the upper tract patient population and considered as an adverse prognostic factor(1). It is thought to be related to advanced tumour stage and a high rate of lymphovascular invasion (2), but the natural history and risk factors are poorly understood. We describe an interesting case of a patient with a retained ureteric stent in the context of stone disease who presented with metastatic TCC with extensive squamous differentiation who required radical surgery.

A 43-year-old man presented with weight loss, night sweats and haematuria. This was in the context of a ureteric stent placed in 2016 in the setting of a single ureteric stone. On recent imaging, it was noted that he had a hypodense left lower pole renal mass measuring 27x38x35mm and an associated 65x51x18mm left retroperitoneal nodal mass invading into the left psoas muscle and hugging close to the aorta between the level of L2-L4. The scan also demonstrated the encrusted retained left ureteric stent with bilateral partial staghorn formation. The mass was suspicious for malignancy and thought to be related to the longstanding retention of the ureteric stent. Patient consent was gained. A review of the literature was performed, and patient information and clinical media was collected.

The patient was placed in the supine position. A midline laparotomy incision was made. The left renal unit was exposed and a radical left nephroureterectomy was performed. A cystostomy then was required to remove the severely encrusted retained stent. Next, careful dissection of the great vessels around and off a large inflammatory necrotic rind overlying the left psoas, originating from the dense left retroperitoneal mass was performed to better identify the vascular anatomy. Then, a limited right RPLND was carried out on the exposed aorta. Finally, tumour debulking of the necrotic psoas was performed and respective specimens were sent for histopathology. The patient was admitted to ICU for routine monitoring and was discharged to the ward two days later. Interestingly, despite extensive psoas resection, he experienced minimal to no neurological deficit. He had an uncomplicated post operative stay and discharged home D10 post op. Post operative histopathology revealed TCC with extensive squamous differentiation.

We describe a case in which long term mechanical irritation of the upper collecting system precipitating the development of TCC with extensive squamous differentiation. This connection has been commented on in pre-existing literature. More research is needed to understand the natural history and precipitating factors for squamous differentiation in upper tract TCC. Furthermore, we emphasize that it is important to treat retained stents before malignant transformation secondary to chronic inflammation.