A 69-year-old female presented with painless haematuria. She was diagnosed with adenocarcinoma of the caecum in 2019 and underwent a right hemicolectomy with segmental resection of the ileum and resection of solitary liver metastasis. CT examination during follow-up three years later revealed a formation in the apex of the bladder. There were no signs of hydronephrosis or hydroureters. The patient complained of occasional gross haematuria but had no other urinary symptoms. Cystoscopy without the biopsy revealed an exophytic formation of the bladder wall. Urine cytologic examination with immunocytochemistry was performed to confirm the diagnosis, although it is not the standard method for the diagnosis. It revealed the presence of cells with the immunophenotype of colorectal adenocarcinoma.
Non-contrast CT examination demonstrated polypoid intraluminal isodense soft-tissue formation in the bladder wall of the apex, measuring 3 x 2 cm (Figure 1). After contrast administration, the broad-based and lobulated lesion appeared homogeneously enhanced (Figure 2). There were no signs of extravesical extension or regional lymphadenopathy.
MRI demonstrated a formation of the bladder dome that appeared slightly hyperintense on T2-weighted image (Figure 3) and isointense on T1- weighted image. The lesion did not show the uptake of the contrast agent in arterial phase and it demonstrated homogeneous enhancement in venous phase (Figure 4).
Secondary bladder neoplasms are rare and represent about 2% of bladder malignancies . They are divided into three subtypes: direct extension of carcinoma from the adjacent organ, metastases, and lymphomas and leukaemias . The most common route of spread is a direct extension of the tumour from surrounding organs [2,3].
Bladder metastases usually appear many years after the primary cancer diagnosis . Metastatic spread can occur via lymphogenous or haematogenous routes, as well as through re-implantation of cells from tumours of the urinary tract . They are frequently associated with metastatic disease and poor prognosis. The most frequent locations of primary carcinoma are colon and rectum, prostate and cervix. Rare cases of breast, lung and skin cancers with bladder metastases have been described in the literature as well .
The most common histological subtype of bladder metastasis is adenocarcinoma, followed by squamous cell carcinoma and other subtypes .
Patients with bladder metastases may be asymptomatic or have urinary symptoms such as painless gross haematuria, pelvic pain, and voiding symptoms, including frequency, urgency and dysuria. In advanced disease, unilateral or bilateral hydronephrosis can occur .
Bladder metastases may show different patterns of tumour growth. A solitary nodular lesion results from focal thickening of the bladder wall, while a diffuse thickening of the bladder wall mostly demonstrates an infiltrative pattern of tumour growth [4,5].
Ultrasound is the first-line diagnostic examination in patients with urinary symptoms [5,6]. We can use ultrasound to detect bladder wall abnormalities and associated complications such as hydronephrosis and ascites.
CT examination is performed to detect tumour formations of the bladder wall and the distant metastases at the same time . Both imaging techniques are useful for detecting pathological findings, but they may not be precise enough for local staging.
MRI is the imaging modality of choice for local staging of bladder carcinomas . It represents the best diagnostic tool for assessing the extent of the bladder wall and extravesicular invasion due to its high soft-tissue contrast. All imaging modalities require optimal bladder distention for accurate assessment.
Metastases to the urinary system from non-urinary primary tumours are relatively rare. The distinction between bladder metastasis and primary bladder carcinoma is often difficult. Urothelial carcinoma of the bladder is an important differential diagnosis. It appears as a T1-isointense and T2-hyperintense lesion, but an early enhancement in the arterial phase distinguishes it from the metastasis of the bladder [7,8]. In our case, urachal carcinoma is a relevant differential diagnosis due to the location of the tumour. Imaging features pathognomonic for urachal carcinoma include calcifications and low-attenuation areas, which represent mucinous components . The standard examination for confirming the diagnosis is cystoscopy with biopsy of the lesion . The immunohistochemical staining of tumour cells is critical for diagnosis and consequently for staging of disease, determining appropriate treatment and prognosis .
Teaching points: Bladder metastases are extremely rare and usually they appear many years after the primary cancer diagnosis. Patients may present with or without urinary symptoms. While ultrasound and CT imaging can detect pathological findings of the bladder wall, MRI is the modality of choice for local staging. Cystoscopy with biopsy of the lesion is the standard examination for confirming the diagnosis of the bladder metastasis.
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