PA27.{14,16} | Renal & Urothelial Tumours — Summary & Reflection

REFLECT

Take 3–4 minutes to reflect on these questions before looking at the summary:

1. A patient with clear cell RCC has a haemoglobin of 19.2 g/dL. Your registrar says 'the tumour is making EPO'. Explain the molecular chain of events from VHL loss to EPO production — can you write it out in 4 steps without looking?

1. You are examining a child with a huge abdominal mass. What single clinical sign on palpation helps you distinguish Wilms tumour from neuroblastoma?

1. A factory worker who has been exposed to aniline dyes for 20 years develops bladder cancer. His tumour is removed, but it recurs within 18 months at a different site in the bladder. What concept explains this recurrence pattern, and what surveillance strategy should follow?

KEY TAKEAWAYS

Renal & Urothelial Tumours — Core Points

Benign renal tumours:
• Oncocytoma — intercalated cell origin; mahogany-brown; central stellate scar
• Angiomyolipoma — hamartoma; sporadic or tuberous sclerosis; fat on CT
• Papillary adenoma — ≤15 mm; incidental

RCC (clear cell — prototype):
• Genetics: VHL loss (3p25) → HIF-1α↑ → VEGF/EPO↑
• Gross: yellow-golden upper-pole mass, pseudocapsule
• Micro: clear lipid-rich cells, thin sinusoidal vessels
• Classic triad (haematuria + flank pain + mass) — only ~10%; most found incidentally
• Paraneoplastics: polycythaemia (EPO), hypercalcaemia (PTHrP), Stauffer syndrome
• Spread: renal vein → IVC → right heart; cannonball lung mets; late recurrence

RCC subtypes: clear cell (VHL, 3p) > papillary (MET, trisomy 7/17) > chromophobe (multiple monosomies)

Wilms tumour (nephroblastoma):
• Commonest renal tumour of childhood (2–5 years)
• WT1 gene (11p13); WAGR and Denys–Drash syndromes
• Triphasic histology: blastemal + epithelial + stromal
• Painless abdominal mass; does not cross midline; excellent prognosis

Urothelial carcinoma:
• Bladder >> renal pelvis; male predominance
• Risk: smoking (commonest), aromatic amines (occupational), cyclophosphamide (acrolein)
• Schistosomiasis → SCC (not UC)
• Painless haematuria; papillary (low-grade) vs. flat CIS (high-grade, progression risk)
• Field cancerisation → multifocal, high recurrence, lifelong cystoscopy
• T2 (muscularis propria) = the critical staging boundary