Clear cell sarcoma of the kidney in an adult: a case report and literature review

Clear cell sarcoma of the kidney (CCSK) in adults is extremely rare. In fact, only 16 adult CCSK cases have been reported from 1989 to 2020 in the English language literature. The pathologic diagnosis of the disease is difficult, and the optimal treatment is still unknown. Currently, no literature review has been done on adult CCSK patients. Herein, we report the case of a 24-year-old man who presented with right flank pain for one month. The patient underwent a series of diagnostic tests, and imaging examinations revealed a large mass in his right kidney. The patient underwent retroperitoneal laparoscopic nephrectomy and regional lymphadenectomy. Pathological examination of the tumor revealed nests and cords of fairly uniform oval cells with clear cytoplasm. Immunohistochemistry showed that the tumor cells were positive for vimentin, CyclinD1, and Bcl-2 and that the sample was uniformly negative for Wilms’ tumor 1 (WT1), CD34, desmin, and cytokeratin staining. Based on these histopathological and immunohistochemical results, the patient was diagnosed with CCSK. The patient subsequently refused chemotherapy and radiotherapy. During the 2-year follow-up, no recurrence or metastasis was observed. We reviewed the English language literature on adult CCSK published in the PubMed database. A pooled analysis was performed, and the results suggested that an accurate pathological diagnosis of CCSK could be achieved based on microscopy and immunohistochemistry. Nephrectomy and regional lymphadenectomy are the main treatments for adult patients with CCSK. While the value of adjuvant radiotherapy and chemotherapy remains controversial, multimodal oncologic treatment, including surgery and chemotherapy with or without radiation, may be efficacious in preventing local recurrence and distant metastases.