Primary fibrosarcoma of kidney in an adult: A diagnostic and therapeutic challenge: A case report and literature review

Background: Primary fibrosarcoma of kidney in adults is a rare entity with a few cases described in the literature. This article will focus on an atypical presentation of this tumor. Summary: We report a case of a 57-year-old male with a 3-year history of intermittent left flank pain, without hematuria or other significant symptoms. Imaging studies, including CT, revealed a large, well-circumscribed mass in the left kidney, initially diagnosed as renal cell carcinoma. The patient underwent a left radical nephrectomy, and histopathological examination revealed a spindle cell proliferation with areas of central necrosis. Immunohistochemistry initially suggested a diagnosis of renal angiomyolipoma. However, six months later, the patient presented with recurrent left-sided lumbar pain and metastases. A re-evaluation of the initial nephrectomy specimen and a biopsy of the retroperitoneal mass confirmed the diagnosis of primary renal fibrosarcoma. The patient is currently receiving chemotherapy. Conclusion: This case illustrates the diagnostic challenges and aggressive nature of primary renal fibrosarcoma. Despite radical nephrectomy, the patient developed rapid recurrence and metastasis, underscoring the poor prognosis of this rare tumor. Further research is needed to establish effective treatment protocols, as current approaches are based primarily on case reports.