Presentation
Extended history of hematuria with non-diagnostic urine/ureteric cytology and pyeloscopic biopsies. Most recent pyeloscopic biopsies showed atypical squamous epithelium. Persistent suspicious radiology prompted surgical treatment.
Patient Data
Upper left kidney partly exophytic solid-appearing heterogeneous isoechoic mass demonstrating no cystic component or internal Doppler flow.
Ill-defined partly exophytic solid-appearing heterogeneous left upper renal mass demonstrating heterogeneous predominately peripheral irregular post contrast enhancement, no associated calcification. The mass is less than 4cm diameter, no perinephric or Gerota's fascia extension, multiple small left para-aortic lymph nodes, no evidence of abdominal spread of disease.
There is a relatively circumscribed but unencapsulated pale lesion in the upper to mid pole of the left kidney. The lesion extends from the medulla, where there is a fungiform protrusion into the renal calyx, all the way to the perinephric surface; there is a focal extension into the perinephric fat in a more posterior slice (not shown).
Low power reconstruction of the renal lesion with fungiform surface component and expansile cortical component showing prominent hyperplastic squamous epithelium.
High power showing well developed squamous differentiation (sometimes incorrectly referred to as 'squamous metaplasia' - this term should be reserved for non-neoplastic reactive changes occurring in benign epithelium.
High power showing poorly differentiated urothelial carcinoma component with poorly formed nests and single infiltrating tumor cells with an associated mixed inflammatory infiltrate.
Case Discussion
This lesion is a poorly differentiated urothelial carcinoma with extensive squamous differentiation.
Squamous differentiation is commonly seen in urothelial carcinoma, but rarely to the extent seen in this lesion (approximately 90% of the tumor showed squamous morphology). A thorough search for conventional urothelial carcinoma is required in these cases as primary squamous cell carcinoma of the kidney/urinary tract should only be diagnosed in the setting of a pure squamous lesion (1)
Many thanks to Dr Vaughan Beckley for contributing the ultasound and CT component of the case