CLINICAL PRESENTATION AND LITERATURE REVIEW: MUSCLE METASTASIS IN UPPER TRACT UROTHELIAL CARCINOMA

Urothelial carcinoma often metastasizes by lymphatic pathways to locations including lymph nodes, bone, and liver. Similar to other cancers, muscle metastasis is uncommon. M.M., a 68-year-old with a history of hypertension, dyslipidemia, and thyroidectomy, has been suffering from lumbar discomfort since April 2023. CT scans revealed secondary lesions and infiltrating urothelial neoplasia in the kidney, renal pelvis, and abdomen. An FDG PET scan confirmed right renal neoplasia. The patient was treated with platinum-based chemotherapy, followed by avelumab. In the sixth cycle, the patient experienced severe pain in the left thigh and a painful mass. MRI of the left thigh confirmed the suspicious origin of the mass, located in the adductor muscle compartment. A PET scan showed clear morphometabolic progression in the right (para)renal locoregion, likely including invasion of the peritoneum, muscles, and right adrenal gland. Pathology confirmed the metastatic origin of the muscle mass.
We decided to give enfortumab vedotin based on the ECOG performance scale (PS) and radiotherapy for the painful metastasis in the left thigh. he patients condition worsened during hospitalization, causing intermittent bewilderment. An brain MRI showed asymmetric pachymeningeal enhancement of the right convexity, indicating meningoencephalitis. A lumbar puncture confirmed the diagnosis, and acyclovir was administered. However, the patient succumbed five days after antibiotic therapy. The literature research revealed 18 documented instances of urothelial cell carcinoma with muscle metastases, all of which were male and involved the bladder. This instance underscores the need to meticulously assess all muscular discomfort in patients with a history of malignancy, as it may indicate skeletal muscle metastases, which correlates with heightened morbidity and death.We present the following case by the CARE reporting checklist.