Imaging identifies suspected right ventricular metastasis from urethral cancer

A 54-year-old man with sarcomatoid urothelial carcinoma of the bulbar urethra developed an enlarging mass in his right ventricle that was initially interpreted as an intracavitary blood clot. Serial contrast echocardiography, FDG PET-CT, cardiac computed tomography and cardiac magnetic resonance imaging subsequently supported a diagnosis of cardiac metastasis. The assessment remained presumptive because no biopsy was performed: the lesion extensively involved the right ventricular apex and myocardium, making sampling carry a substantial risk of perforation.

The case report, published in Frontiers in Oncology, illustrates how multimodality imaging and the course of concurrent extracardiac cancer were integrated to distinguish an aggressive myocardial tumor from thrombus in a patient for whom both explanations were clinically plausible. Primary urethral carcinoma is an uncommon malignancy, accounting for less than 1% of malignancies in Europe and occurring approximately five times more frequently in men than in women. The case involved a non-smoker with no significant medical history who presented with irritative urinary symptoms and hematuria.

Evaluation classified his tumor as cT4N0M0 sarcomatoid urothelial carcinoma of the bulbar urethra, indicating an advanced local primary without detected lymph-node or distant metastases. Urothelial carcinoma is the predominant histological subtype of primary urethral cancer, and the sarcomatoid variant in this case was associated with a rapidly progressive clinical course. Because prospective evidence for primary urethral carcinoma is limited, management is largely based on treatment approaches used for bladder and other histologically related urothelial cancers.

The patient received eight cycles of neoadjuvant dose-dense methotrexate, vinblastine, doxorubicin and cisplatin, abbreviated ddMVAC, through February 2025. He then underwent phallectomy, cystoprostatectomy and Indiana pouch reconstruction in March 2025. Histopathological examination showed high-grade G3 sarcomatoid urothelial carcinoma with a 5% giant-cell component, downstaged to ypT2ypN0, with no tumor found in any of 16 examined lymph nodes.

Venous and lymphovascular invasion and associated urothelial carcinoma in situ were nevertheless present. The surgical specimen showed a PD-L1 tumor proportion score of 20%, and adjuvant nivolumab began in May 2025. Only three months into nivolumab treatment, the patient developed fever and left lumbar pain.

CT urography revealed a heterogeneous lesion in the prostatic and right seminal-vesicle surgical bed, raising concern for locoregional recurrence, and also identified a filling defect at the right ventricular apex. A clot was a credible initial interpretation because the patient had active cancer, had recently undergone major pelvic surgery and was found to have a chronic-appearing segmental pulmonary embolus. Therapeutic anticoagulation with tinzaparin was therefore started.

Lower-extremity Doppler ultrasonography did not identify deep-vein thrombosis. Contrast-enhanced transthoracic echocardiography showed mid-apical right ventricular akinesia and a 34-by-28-millimeter apical mass that remained compatible with thrombus. Treatment of a concomitant Klebsiella pneumoniae urinary tract infection was followed by resolution of the fever and lumbar pain.

Pelvic MRI in September 2025 showed progression of the surgical-bed lesion and new nodular disease involving the anterior pelvic peritoneal fascia, left ilio-obturator region, perineum and the former urethral tract, consistent with locoregional recurrence. FDG PET-CT in October 2025 confirmed hypermetabolic pelvic disease and showed intense FDG uptake in the right ventricular mass, which measured 65 by 35 millimeters and had a maximum standardized uptake value of 14.9. The mass contained a central hypometabolic component.

A small hypermetabolic pulmonary nodule was also detected, with an SUVmax of 3.7. Follow-up echocardiography showed further enlargement of the right ventricular mass to 52 by 30 millimeters. Its continued growth despite anticoagulation over approximately two months substantially reduced the likelihood that it was a bland thrombus and prompted more extensive characterization.

For metastatic disease, enfortumab vedotin was initiated in October 2025 at 1.25 milligrams per kilogram on days 1, 8 and 15 of each 28-day cycle. Treatment was generally well tolerated, with mild asthenia, pruritus, peripheral neuropathy and alopecia. A multidisciplinary group comprising oncologists, cardiologists, cardiothoracic surgeons, radiologists and nuclear-medicine specialists reviewed the case.

Cardiac CT demonstrated a heterogeneous 58-by-53-by-38-millimeter mass with predominantly peripheral enhancement and a central hypodense core. Cardiac MRI showed that the lesion was not simply floating within the ventricular cavity: it arose from the apical septum and ventricular apex, extended intracavitarily and infiltrated the adjacent interventricular septum and right ventricular free wall. Heterogeneous first-pass perfusion and late gadolinium enhancement supported a vascularized neoplastic lesion rather than bland thrombus, while the central nonenhancing component was suggestive of intratumoral necrosis.

The infiltrating mass restricted right ventricular systolic function and mildly reduced the right ventricular ejection fraction to 41%. Surgical resection was considered infeasible because the extent of myocardial infiltration created a risk of ventricular perforation, while cardiac biopsy was judged prohibitively risky for the same anatomical reasons. The clinicians also reasoned that tissue confirmation was unlikely to change systemic treatment because the patient already had clear locoregional and pulmonary progression.

Histology nevertheless remains the diagnostic reference standard, making this a presumptive diagnosis rather than a pathologically confirmed metastasis. No autopsy was performed after the patient’s death, so postmortem confirmation was unavailable. FDG uptake was informative but not specific for malignancy: inflammatory lesions and organized thrombi can also be metabolically active.

Its importance in this case came from its interpretation alongside other evidence, including the mass’s enlargement despite anticoagulation, intense uptake, apparent myocardial origin, invasion of adjacent tissue and simultaneous progression of pelvic and pulmonary disease. The absence of the lesion on earlier imaging and the extent of extracardiac progression made a primary cardiac neoplasm less likely, although it could not be excluded. The right ventricular apex is also an acknowledged echocardiographic blind spot, further limiting the diagnostic value of a single examination.

Together, the findings favored a right ventricular myocardial metastasis from the known urethral carcinoma, while retaining uncertainty about its exact histology and cellular composition. The response to enfortumab vedotin was markedly heterogeneous. The cardiac and pulmonary metastases remained relatively stable for about three months, while the locoregional pelvic disease continued to progress.

In December 2025, escalating pelvic pain required opioid escalation and prompted palliative radiotherapy at 36 gray in 12 fractions. This provided temporary partial symptomatic relief, but subsequent pelvic and pulmonary progression led to discontinuation of radiotherapy. Exertional dyspnea worsened despite persistent stability of the ventricular mass on echocardiography and the presence of only a minimal pericardial effusion.

The patient’s functional status declined despite supportive measures including home oxygen and transfusion support. He entered palliative care in March 2026 after recurrent severe dyspnea and subsequently developed progressive somnolence, hyporexia, pulmonary congestion and intestinal obstruction. He died seven days after admission, 17 months after the initial diagnosis.

Several possible biological explanations for the uneven treatment response remain exploratory. Sarcomatoid urothelial carcinoma may develop through epithelial-to-mesenchymal transition and contain variable proportions of epithelial and sarcomatoid components. If that transition occurs to different degrees in separate deposits, lesions could respond differently to the same systemic therapy.

Differences in nectin-4 expression offer another potential explanation, because lower expression has been associated in retrospective studies with reduced sensitivity to enfortumab vedotin. Neither nectin-4 expression nor the component makeup of the cardiac lesion was assessed in this patient, however, and no paired tissue was available from the presumed metastasis to test these hypotheses. Molecular profiling of the primary surgical specimen identified a pathogenic PIK3CA H1047R variant with a 15% variant allele frequency.

Its prognostic significance has been inconsistent across urothelial carcinoma treatment settings, and PIK3CA status does not currently guide treatment selection in bladder or urethral carcinoma. The case therefore documents both a difficult noninvasive diagnosis and a therapeutic problem: multimodality imaging strongly supported a myocardial metastasis, but the absence of tissue confirmation limited certainty, and enfortumab vedotin did not prevent relentless progression of the primary and regional disease.

Subject of Research: Multimodality imaging of a suspected right ventricular metastasis from sarcomatoid urothelial carcinoma of the urethra

Article Title: Sarcomatoid urothelial carcinoma of the urethra with an unusual right ventricular metastasis: a case report and review of literature

Article References: Yaringaño, J., Calvo-Losada, J., Oristrell, G., Semidey, M. E., Marmolejo, D., Geng-Cahuayme, A. A., Simó, M., Mast, R., Suárez, C., Carles, J., & Morales-Barrera, R. (2026). Sarcomatoid urothelial carcinoma of the urethra with an unusual right ventricular metastasis: a case report and review of literature. Frontiers in Oncology, 16, Article 2003381. https://doi.org/10.3389/fonc.2026.2003381

Image Credits: AI Generated

DOI: 10.3389/fonc.2026.2003381

Keywords: sarcomatoid urothelial carcinoma, primary urethral cancer, cardiac metastasis, right ventricular mass, multimodality imaging, cardiac MRI, FDG PET-CT, cardiac thrombus, enfortumab vedotin, case report, Sarcomatoid, urothelial