Case report: A case of primary renal osteosarcoma

Rationale: Primary renal osteosarcoma is an exceedingly rare malignant tumor. Fewer than 30 cases have been reported in the literature since 1936. Furthermore, it has a high risk of metastasis and a poor overall prognosis rate. Patient’s concerns: In this report, we present a case of osteosarcoma originating from the left kidney (21 cm × 18 cm × 11 cm) with adhesions of the descending colon mesentery and the abdominal wall. A 63-year-old male patient presented with flank pain and gross hematuria. Diagnoses: A computed tomography scan revealed that the lesion with irregular margins was observed at the lower pole of the left kidney. Enhanced CT scan showed significant inhomogeneous enhancement of the lesion, with non-enhancing necrotic areas. A radical nephrectomy was performed. The immunohistochemistry results support the diagnosis of osteosarcoma. Interventions: Postoperatively, the patient participated in clinical trials and received treatment with a PD-1 antibody (2 weeks/once). Outcomes: At the one-year follow-up, the patient reported late-stage systemic cancer-related pain, necessitating daily pain relief medication. Unfortunately, the patient passed away 18 months after the surgery. Lessons: The case reported here is an exceedingly rare malignant osteosarcoma that originated from the kidney with the invasion of the descending colon mesentery and the abdominal wall. The patient received treatment with a PD-1 antibody (2 weeks/once). However, the patient passed away 18 months after the surgery. With the application of genetic testing technology and advancements in molecular biology, it was expected that specific targeted therapies for this condition would emerge in the future.