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TSC Solid Mass Biopsy RCC Exclusion — ESENeph MCQ

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ModerateChronic Kidney DiseaseTSC Solid Mass Biopsy RCC ExclusionESENeph

A 36-year-old man presents with loin pain and macroscopic haematuria. CT shows a 4 cm solid enhancing mass in the right kidney. He has tuberous sclerosis complex (TSC) with multiple bilateral angiomyolipomas. This mass is distinct from his AMLs. What investigation is most important to characterise this mass?

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Correct answer: C — Percutaneous biopsy to exclude renal cell carcinoma

While angiomyolipomas are the most common renal lesion in TSC, patients with TSC also have an increased risk of renal cell carcinoma (RCC). A solid enhancing mass that is distinct from established AMLs requires characterisation — percutaneous biopsy is essential to distinguish RCC from fat-poor AML (which can appear identical on CT). Classic AMLs contain macroscopic fat visible on CT, but fat-poor AMLs lack this diagnostic feature. In TSC, RCC may be of unusual subtypes (e.g., hybrid oncocytic/chromophobe). Nephron-sparing surgery is preferred if RCC is confirmed, given the bilateral AML burden and need to preserve renal mass.

Reference: Bjornsson et al 1996 – TSC Renal Lesions; NICE 2023 – Renal Cancer; European TSC Guidelines 2019