A Stranger in the Backyard: a Rare Case of Retroperitoneal Squamous Cell Carcinoma

Malignancies of the retroperitoneum are uncommon; they may either be primary or arise secondarily from contiguous organs. Primary retroperitoneal carcinomas are extremely rare. Squamous cell carcinoma (SCC) of the renal pelvis is a rare upper urinary tract urothelial carcinoma arising in the setting of chronic nephrolithiasis. Due to locally advanced disease or metastases, these aggressive malignancies are often inoperable at presentation. We report a case of a 55-year-old man, a hypertensive and chronic smoker with a history of analgesic abuse, who underwent left nephrectomy for a non-functional kidney (chronic pyonephrosis with stag-horn calculus). Histopathological examination of the specimen was neglected and the patient presented 4 months later with advanced, inoperable retroperitoneal SCC which could only be palliated. This article highlights the prognosis associated with renal SCC and the importance of early detection in improving outcomes; periodic imaging with biopsy of suspicious mass lesions should be advocated in patients with renal calculous disease especially stag-horn calculi. Exclusion of malignancy prior to nephrectomy (when indicated) and HPE of the resected specimen is crucial in management. Radical nephrectomy may merit consideration in patients with non-functional kidneys secondary to long-standing nephrolithiasis when malignancy is suspected.