Urothelial carcinomas, which comprise nearly 90% of bladder tumors, usually appear as superficial or muscle-invasive types; however, rare histological variants such as those with sarcomatoid differentiation tend to follow a significantly more aggressive clinical trajectory (3). Sarcomatoid urothelial carcinomas are biphasic tumors that contain both epithelial and mesenchymal components (4). These tumors are frequently high-grade, tend to invade deep tissues, and are prone to early metastasis (5). Reported incidence in the literature ranges from 0.3% to 1%, with most cases being diagnosed at an advanced stage (pT3–pT4) (2). Variant histology has been reported as an independent factor negatively affecting pathological outcomes and survival in urothelial carcinoma; sarcomatoid differentiation is considered one of the most aggressive subtypes (1). Tumors containing a sarcomatoid component often exhibit adverse histopathological features, such as tumor necrosis, perineural invasion, and lymphovascular invasion, all of which negatively impact overall survival. Studies have shown that this variant is associated with significantly shorter survival compared to conventional urothelial carcinomas (6). The frequent detection of widespread metastasis or locally advanced invasion at the time of diagnosis further underscores the biologically aggressive nature of these tumors. While intravesical therapies remain essential for non–muscle invasive bladder tumors, especially in the setting of BCG failure, where combination strategies such as BCG plus interferon-α2b have been reported, sarcomatoid differentiation typically presents with advanced disease that necessitates radical surgical management. In the present case, the tumor demonstrated perivesical adipose tissue invasion beyond the bladder (pT3b), metastasis in the right pelvic lymph node, and, notably, a rare colonic metastasis. While urothelial carcinomas most commonly metastasize to the liver, lungs, and bones, involvement of the gastrointestinal system is exceedingly rare (7). In particular, reports of invasion into the colon and the presence of metastatic foci within the mesocolon are limited to a small number of cases in the literature. A review of the existing literature suggests that colonic involvement in sarcomatoid urothelial carcinoma has been described in only a limited number of case reports. In one of those reports, a patient who had previously undergone partial cystectomy presented to the emergency department three months postoperatively with abdominal pain, and advanced imaging revealed a mass in the transverse colon. Surgical resection and subsequent pathological analysis identified urothelial carcinoma with sarcomatoid differentiation (8). In another case report, the patient with bladder urothelial carcinoma was found to have an isolated gastric metastasis (9).
The lesion mimicked a primary gastric tumor, highlighting the importance of considering metastatic disease in patients with atypical gastrointestinal findings (1). These findings suggest that the sarcomatoid component may enable metastasis to atypical organs via lymphatic or hematogenous spread.
This case contributes to the literature by highlighting the potential for atypical dissemination patterns in bladder tumors and underlining the worse prognosis associated with the sarcomatoid variant.
DISCUSSION
Urothelial carcinomas, which comprise nearly 90% of bladder tumors, usually appear as superficial or muscle-invasive types; however, rare histological variants such as those with sarcomatoid differentiation tend to follow a significantly more aggressive clinical trajectory (3). Sarcomatoid urothelial carcinomas are biphasic tumors that contain both epithelial and mesenchymal components (4). These tumors are frequently high-grade, tend to invade deep tissues, and are prone to early metastasis (5). Reported incidence in the literature ranges from 0.3% to 1%, with most cases being diagnosed at an advanced stage (pT3–pT4) (2). Variant histology has been reported as an independent factor negatively affecting pathological outcomes and survival in urothelial carcinoma; sarcomatoid differentiation is considered one of the most aggressive subtypes (1). Tumors containing a sarcomatoid component often exhibit adverse histopathological features, such as tumor necrosis, perineural invasion, and lymphovascular invasion, all of which negatively impact overall survival. Studies have shown that this variant is associated with significantly shorter survival compared to conventional urothelial carcinomas (6). The frequent detection of widespread metastasis or locally advanced invasion at the time of diagnosis further underscores the biologically aggressive nature of these tumors. While intravesical therapies remain essential for non–muscle invasive bladder tumors, especially in the setting of BCG failure, where combination strategies such as BCG plus interferon-α2b have been reported, sarcomatoid differentiation typically presents with advanced disease that necessitates radical surgical management. In the present case, the tumor demonstrated perivesical adipose tissue invasion beyond the bladder (pT3b), metastasis in the right pelvic lymph node, and, notably, a rare colonic metastasis. While urothelial carcinomas most commonly metastasize to the liver, lungs, and bones, involvement of the gastrointestinal system is exceedingly rare (7). In particular, reports of invasion into the colon and the presence of metastatic foci within the mesocolon are limited to a small number of cases in the literature. A review of the existing literature suggests that colonic involvement in sarcomatoid urothelial carcinoma has been described in only a limited number of case reports. In one of those reports, a patient who had previously undergone partial cystectomy presented to the emergency department three months postoperatively with abdominal pain, and advanced imaging revealed a mass in the transverse colon. Surgical resection and subsequent pathological analysis identified urothelial carcinoma with sarcomatoid differentiation (8). In another case report, the patient with bladder urothelial carcinoma was found to have an isolated gastric metastasis (9).
The lesion mimicked a primary gastric tumor, highlighting the importance of considering metastatic disease in patients with atypical gastrointestinal findings (1). These findings suggest that the sarcomatoid component may enable metastasis to atypical organs via lymphatic or hematogenous spread.
This case contributes to the literature by highlighting the potential for atypical dissemination patterns in bladder tumors and underlining the worse prognosis associated with the sarcomatoid variant.