Cardiac and Intramuscular Metastases Following Nephroureterectomy for Metachronous Urothelial Carcinoma

BACKGROUND We present a case of metachronous cardiac and intramuscular metastases in a patient with a known history of radical nephroureterectomy for upper-tract urothelial carcinoma (UTUC). CASE REPORT A 58-year-old man had a history of metachronous renal pelvis urothelial carcinoma with prior left radical nephroureterectomy. He was also diagnosed with malignancy-associated deep vein thrombosis (DVT) and was on rivaroxaban. He presented at an oncology follow-up consult with shortness of breath and right scapular lump. CT scan revealed a soft-tissue mass at the surgical bed suspicious for local recurrence, as well as intracardiac hypodensities and intramuscular nodules in the right latissimus dorsi and right adductor muscles. The intracardiac hypodensities were located in the left atrial appendage and inter-atrial septum. Given that the patient had a history of DVT and in a pro-thrombotic state, differentials for the intracardiac densities included intracardiac thrombi or metastases. The intramuscular hypodensities were rim-enhancing. Given that the patient was on rivaroxaban, differentials included hematomas or metastases. As there was no overlying bruising and the lesions remained unchanged in size clinically, they were treated as metastases. The patient was treated with clexane but re-presented with worsening of shortness of breath and palpitations. CT scan showed increased size of intracardiac lesions, suggesting no response to anticoagulation, and therefore were likely metastatic in nature. He completed a 2-year course of IV pembrolizumab and was in complete remission. CONCLUSIONS Our case highlights the importance of this clinically challenging scenario when patients with known malignancy and on anticoagulation present with cardiac or musculoskeletal symptoms. Though these patients are at risk of thrombus and haematoma, cardiac and intramuscular metastasis should be considered, as the prognosis is guarded.