Primary renal parenchymal squamous cell carcinoma mimicking abscess: value of trans-urinary tract fine-needle aspiration in preoperative evaluation: a case report and literature review.

Primary squamous cell carcinoma (SCC) of the renal parenchyma is exceedingly rare, with only seven cases reported to date. We report a 72-year-old woman with recurrent cystitis, gross hematuria, and a right renal mass. Imaging studies revealed a necrotic lesion in the renal parenchyma, initially suggestive of an abscess. Despite percutaneous drainage and antibiotic therapy, there was no clinical improvement. Trans-urinary tract fine-needle aspiration (FNA) provided preoperative cytologic evidence of malignancy with features consistent with SCC, and histopathologic examination of the nephrectomy specimen, supported by immunohistochemistry, confirmed primary renal parenchymal SCC. The patient subsequently underwent radical nephrectomy, and histopathological examination confirmed a primary SCC of the renal parenchyma without renal pelvic involvement. Although surgical treatment was performed promptly, metastatic spread to lymph nodes, vertebrae, and lungs was detected within months, and the patient died 18 months postoperatively. This case highlights the importance of considering SCC in the differential diagnosis of abscess-like renal lesions, particularly when they fail to respond to antibiotics. In selected patients, trans-urinary tract FNA offers a rapid, minimally invasive means to obtain cytologic material, which can prevent delays and facilitate timely management, potentially improving outcomes in similarly challenging cases. Additional studies will clarify diagnostic and therapeutic strategies.