Primary squamous cell carcinoma of renal pelvis and kidney- Sole diagnosis by histopathology

Primary Squamous cell carcinoma of the renal pelvis is rare and accounts to only 0.5- 0.8 % of malignant renal tumours having poor prognosis. Chronic irritation, inflammation and infection induce the pathogenesis of this malignancy. A 53 year old male patient, presented with left flank pain since one month. On radiological investigation, his CT revealed atrophic shrunken left kidney measuring 7.9x5.2cms showing significant parenchymal thinning and complete loss of corticomedullary differentiation. A left upper ureteric calculus is seen measuring 7.5 mm with significant left renal hydronephrosis.Clinically, it was diagnosed as Xanthogranulomatous Pyelonephritis. Grossly the radical nephrectomy specimen measures 10.5x5.5x3.5cm. External surface is irregular & bosselated. On Cut surface renal architecture is effaced by necrotic mass measuring 9.5x5.0x3.0 cm involving pelvic ureter and most of renal parenchyma.Hematoxylin and eosin stained tissue revealed characteristic feature such as keratin pearls and intracellular bridges seen, rendering the diagnosis of well-differentiated keratinising squmaous cell carcinoma seen with 40% tumour necrosis associated with Keratinizing Squamous Dysplasia. In the present case, obstructive uropathy has triggered the event of malignancy. The radiologic differential diagnosis includes primary and secondary renal neoplasms and xanthogranulomatous pyelonephritis associated with renal calculi. XGP is commonly associated with lithiasis however, rarely causes keratinizing squamous metaplasia and its manifestations closely mimic renal neoplasm, leading to misdiagnosis of malignancy.The prognosis is dismal with a 5-year survival rate of <10%. CT and MRI play a crucial role in diagnosis and staging of these tumors, though histology always remains confirmatory and diagnostic.