Multimodal imaging clarifies cardiac mass in sarcomatoid urethral carcinoma despite relentless locoregional progressionMultimodal Imaging Helps Detect Heart Issues in Rare Urethral Cancer

Primary urethral carcinoma is an uncommon malignancy, and cardiac metastasis represents a rare event (~4% of cases) that poses significant diagnostic challenges, particularly in distinguishing myocardial tumors from intracavitary thrombi. Here we report a 54-year-old male diagnosed with cT4N0M0 sarcomatoid urothelial carcinoma of the bulbar urethra. Following neoadjuvant dose-dense MVAC and radical surgery (ypT2N0, PD-L1 TPS 20%), adjuvant nivolumab was initiated. Six months after surgery, he developed locoregional recurrence and an expanding right ventricular mass. Multimodality cardiac imaging—including contrast echocardiography, FDG PET-CT, cardiac CT, and cardiac MRI—demonstrated a solid myocardial lesion with intracavitary extension and adjacent myocardial infiltration, considered highly suspicious for cardiac metastasis in the context of concurrent extracardiac progression. Histological confirmation was not obtained because of the procedural risk associated with extensive right ventricular involvement. Treatment with enfortumab vedotin yielded relative stability of the cardiac and pulmonary metastases; however, relentless locoregional progression occurred, illustrating interlesional response heterogeneity. The patient subsequently received palliative radiotherapy, and best supportive care before passing away 17 months after initial diagnosis. This case underscores the vital role of multimodal imaging in the differential diagnosis of cardiac masses in oncological patients with concurrent thromboembolic risk and its interpretation in conjunction with the disease course when pathology confirmation cannot be obtained. Furthermore, it highlights the therapeutic complexity and dismal prognosis associated with sarcomatoid histology in advanced urethral carcinoma.