RESUMEN
A 65-year-old male was admitted to our hospital with an abscess on his buttocks. Computed tomography (CT) on admission incidentally revealed left kidney cancer, and retroperitoneal nephrectomy was performed. Pathological examination confirmed a diagnosis of renal cell carcinoma. One month after surgery, CT showed findings suggesting primary liver cancer or liver metastasis along with retroperitoneal metastasis. Although metastatic kidney cancer was suspected, the possibility of primary liver cancer could not be ruled out. Therefore, we initiated treatment using sorafenib, which is indicated for both types of cancer, as first-line treatment for intermediate-risk based on the International Metastatic Renal Cell Carcinoma Database Consortium (IMDC) risk classification. After three months of sorafenib treatment, the patient showed hyponatremia, anemia, and hand-foot syndrome and was admitted to the hospital. CT showed an enlarged area that appeared to be a metastatic site, after which we suspended sorafenib. Four months after sorafenib treatment, nivolumab was initiated as a second-line treatment. However, on day 28 after the administration of nivolumab eruptions appeared all over the patient's body. The patient was diagnosed with Stevens-Johnson syndrome due to nivolumab. We initiated corticosteroid therapy, and the eruptions gradually improved. Prednisolone was gradually reduced to 5mg/day, after which the patient was discharged. Six months after discharge, the eruptions had generally become epithelialized and no metastatic lesions had grown. The patient remained under observation without proceeding to third-line treatment. It is crucial to carefully monitor the patient's condition, especially in cases involving serious immune-related adverse events.