Teaching Case

Our institution has been monitoring a 33-year-old male patient with surgically reconstructed bladder exstrophy and epispadias, still suffering from chronic urinary retention and recurrent urinary tract infections. While undergoing nephrostomy for bilateral pyonephrosis, the right renal vein was lacerated, so a CT scan was requested to evaluate the retroperitoneal haematoma.

In addition to the retroperitoneal haematoma, non-enhanced CT revealed a large pelvic mass displacing the surrounding structures, undetermined but highly suspicious for malignancy (Figure 1).

Further characterisation by MR confirmed the presence of an aggressive-appearing solid mass (Figure 2), which replaced the prostate, the seminal vesicles, and most of the bladder wall, explaining the bilateral hydronephrosis. It showed relatively well-defined contours and heterogeneous intermediate and high T2 signals, with extensive areas of central necrosis. Given the patient’s background and aggressive imaging features, a malignant mesenchymal tumour and squamous cell carcinoma were considered the most probable, although their origin could not be ascertained.

A biopsy of the tumour was then performed by a transrectal approach, revealing clear-cell squamous carcinoma with extensive tumour necrosis, most probably arising from the bladder wall.

Since only one regional lymphadenopathy had been seen, with no signs of distant metastases, the patient was submitted to pelvic exenteration.

Squamous cell carcinoma (SCC) is a highly aggressive form of bladder cancer, accounting for 3–5% of all bladder malignancies in Western countries [1]. It is strongly linked to chronic bladder inflammation, driven by an indwelling bladder catheter, recurrent urinary tract infections, schistosomiasis, bladder calculi, intravesical BCG therapy, or smoking [1–3]. Chronic inflammation leads to squamous metaplasia of the urothelium and potentially results in malignant transformation. Therefore, the pathophysiology of a pure SCC differs from that of urothelial carcinoma (UC) with squamous differentiation, which is defined by divergent differentiation of only a subset of tumour cells and still managed as UC [1,2].

SCC most frequently presents with macroscopic haematuria, although constitutional symptoms, pelvic pain, and signs of urinary obstruction may be present in advanced stages [3,4]. Indeed, 80% of these tumours are locally advanced upon diagnosis [1,3,5] and approximately 10% present with distant metastases, usually in lymph nodes, bone and peritoneum [5].

CT and MR reveal a broad-based polypoid mass, most frequently located in the trigonum and posterior bladder wall. It tends to have a low T1 and intermediate to high T2 signal, as well as areas of central necrosis, rendering it nonspecific by imaging [4]. Bladder wall calcifications are often described in SCC, although this possibly results from its strong association with schistosomiasis [2].

While our patient’s history of chronic bladder inflammation suggested SCC of the bladder, it is important to consider other diagnoses. In the presence of a locally aggressive pelvic mass, one must keep in mind that the mass may have originated in the prostate. Prostatic SSC with bladder invasion also has nonspecific imaging features and could present in a similar fashion. However, no risk factors were present, such as genitourinary schistosomiasis, prior radiation therapy, or androgen suppression, rendering this hypothesis less likely. The moderate to high T2 signal and extensive necrosis must also raise suspicion for a malignant mesenchymal tumour, namely a leiomyosarcoma, which may arise from either the bladder or the prostate [2,5,6]. Finally, a poorly differentiated and a squamous cell differentiated UC must be considered [4].

Radical cystectomy with nodal dissection is the standard treatment of care. Nevertheless, the 5-year survival remains at 48% due to high local recurrence rates. SCC also appears to be relatively resistant to chemotherapy, and the benefit of radiotherapy remains to be proven, accentuating the poor prognosis of patients with unresectable or metastatic disease [1].

All patient data have been completely anonymised throughout the entire manuscript and related files.