A 58-year-old man presents with haematuria and flank pain. Ultrasound shows a 4 cm heterogeneous mass in the right kidney with areas of necrosis. Which investigation is most appropriate for staging and detecting metastases before surgical planning?

Explanation

## Investigation of Choice for RCC Staging **Key Point:** Contrast-enhanced CT (CECT) of chest, abdomen, and pelvis is the gold standard for staging renal cell carcinoma and detecting metastases. ### Why CECT is Superior | Feature | CECT | MRI | PET-CT | Angiography | |---------|------|-----|--------|-------------| | **Sensitivity for RCC** | 95–98% | 90–95% | 70–80% | N/A (invasive) | | **Detects renal vein invasion** | Excellent | Excellent | Poor | N/A | | **Lung metastases** | Excellent | Limited | Good | N/A | | **Bone metastases** | Good | Good | Excellent | N/A | | **Liver metastases** | Excellent | Excellent | Moderate | N/A | | **Speed & availability** | Fast, widely available | Slower | Limited availability | Invasive | | **Contraindications** | Contrast allergy, renal insufficiency | Pacemaker, claustrophobia | N/A | Invasive, thrombosis risk | **High-Yield:** CECT is the **first-line imaging** for RCC because it: 1. Characterizes the renal mass (enhancement pattern, necrosis, calcification) 2. Assesses local invasion (perinephric fat, renal vein, IVC) 3. Detects distant metastases (lung bases, liver, adrenal, contralateral kidney) 4. Is rapid, reproducible, and cost-effective ### Role of Other Investigations **MRI:** Reserved for: - Patients with **contrast allergy** or **severe renal impairment** (eGFR < 30) - Evaluation of **IVC thrombus** (superior to CT for extent) - Pregnancy (though RCC rare in this setting) **PET-CT:** Not recommended for initial staging because: - RCC is **variably FDG-avid** (especially low-grade tumours) - Poor sensitivity for small metastases - Reserved for **suspected recurrence** or high-grade disease **Renal artery angiography:** Obsolete for diagnosis/staging; now only used: - Intraoperatively for nephron-sparing surgery guidance - Preoperative embolization in select cases **Clinical Pearl:** The TNM staging of RCC depends critically on CECT findings: - **T1:** ≤4 cm, confined to kidney - **T2:** >4 cm, confined to kidney - **T3a:** Invasion of renal vein or perinephric fat - **T3b/c:** IVC invasion (CECT + MRI for extent) - **T4:** Invasion of Gerota's fascia - **M1:** Distant metastases (detected on CECT chest/abdomen/pelvis) **Mnemonic: CECT for RCC** = **C**haracterize mass, **E**valuate local **E**xtension, **C**heck for metastases, **T**reatment planning.