Renal Cell Carcinoma

Renal Cell Carcinoma

Todd M. Blodgett, MD

Alex Ryan, MD

Hesham Amr, MD

Graphic shows a typical appearance of a large renal cell carcinoma image with invasion of the renal vein and inferior vena cava image.

Coronal PET (A), axial CT (B) and fused PET/CT (C) show a relatively non-FDG-avid renal cell carcinoma image.


Abbreviations and Synonyms

  • Renal cell carcinoma (RCC), clear cell carcinoma, hypernephroma, renal cancer


  • Carcinoma of renal tubular epithelium


General Features

  • Best diagnostic clue

    • Iso- or hypermetabolic renal mass ± lymphadenopathy, metastases on FDG PET

    • Presents most commonly as incidental solid tumor on imaging

    • Enhancing solitary mass on CT highly suspicious for RCC

      • Necrosis, hemorrhage, septae more likely in large masses

  • Location

    • Usually renal cortex

    • Often exophytic

    • Rarely bilateral (2%) or multicentric (more common in von Hippel-Lindau)

  • Size: Variable depending on time of diagnosis

  • Morphology

    • 10% calcified, often irregular

    • 2-5% cystic

Imaging Recommendations

  • Best imaging tool

    • Combination of CT, ultrasound

      • CECT often shows enhancing lesion; hyperdense benign cysts will not enhance

      • US indicated in patients with nonenhancing hyperdense renal lesions to differentiate cyst from mass

      • If contraindication to contrast, MR superior to CT

    • FDG PET and PET/CT not currently covered by Medicare, but may be helpful for staging and restaging

  • Protocol advice

    • For CT: Noncontrast and CECT, thin sections (2.5-5.0 mm), during both corticomedullary and nephrographic phases

      • For PET CT: If only single phase obtained, use later nephrographic phase of contrast enhancement

    • Corticomedullary phase (25-70 seconds post-injection)

      • Better visualization of renal vessels; evaluate for renal vein/IVC thrombosis or tumor extension

      • Limited detection of small renal lesions

      • Centrally located tumors commonly mistaken for normal hypoattenuating medulla

    • Nephrographic phase (80-180 seconds post-injection)

      • Best imaging of renal medulla masses

CT Findings

  • NECT

    • Solid-tissue-density mass, which distorts normal kidney contour and typically is in the 30-50 HU range

    • Can be hyperdense, isodense, or hypodense to surrounding normal kidney

    • Heterogeneous mass (hemorrhage and necrosis); high (acute hemorrhage) or low attenuation (chronic)

      • ± Calcifications (10% of cases); amorphous internal (most common), curvilinear (peripheral or central), dense or diffuse calcification

    • High density rim may separate mass from adjacent renal tissue (pseudocapsule)

    • Rarely contains small areas of fat (-50 to -150 HU)

    • Combination of fat and calcification suggests RCC, not renal angiomyolipoma

    • Cystic RCC

      • Uni- or multilocular cystic mass with a thick calcification of septa or tumor capsule

      • Septa may enhance on CECT

  • CECT

    • Hypervascular mass with enhancement (HU increase by > 20) compared to noncontrast

      • Enhancement often heterogeneous, particularly larger lesions

    • Tumor extension or thrombus in renal vein (23%), inferior vena cava (7%)

    • Local extension common

      • Nodal spread typically to para-aortic or aortocaval lymph nodes

    • Most common metastatic locations include lung, liver, bone, adrenal, and opposite kidney

    • Usually solid, and decreased attenuation suggestive of necrosis often present

    • Sometimes presents as predominantly cystic mass with thick septa and wall nodularity

    • Nephrographic phase is most sensitive for tumor detection, especially for masses smaller than 3 cm

    • Corticomedullary phase required for tumor extension into renal veins

      • Evaluation for hypervascular metastases

    • Helical CT improves diagnosis and eliminates respiratory misregistration

Nuclear Medicine Findings

  • FDG PET and PET/CT for RCC

    • Iso- or hypermetabolic renal mass ± lymphadenopathy, metastases

    • FDG uptake by primary RCC and metastases is somewhat variable; therefore, PET and PET/CT are more helpful when positive

      • Negative study may represent either a non-FDG-avid RCC or truly negative disease

    • Sensitivity 60%, specificity ˜ 100% for evaluating primary RCC

    • Excretory FDG in collecting system can mask small RCCs adjacent to collecting system

    • 80-100% specific for bony metastases


Angiomyolipoma (AML)

  • Fat attenuation (-30 to -150 HU) fairly specific for this neoplasm

  • Low FDG uptake

  • Reliably distinguished from malignancy by CT characteristics

Renal Oncocytoma

  • Central scar on CT/MR and spoke-wheel pattern of vessels on angiograms suggest oncocytoma; not entirely specific

  • Cannot confidently differentiate from RCC by PET

Hemorrhagic Renal Cyst

  • > Water attenuation on CT (˜ 30-70 HU)

  • Should not enhance when comparing noncontrast and CE series

Transitional Cell Carcinoma (TCC)

  • Renal pelvis filling defect, narrowing

  • Urothelial thickening or involvement

  • Rare parenchymal TCC indistinguishable from RCC


  • Typically more diffusely infiltrative than discrete mass

Renal Infection or Abscess

  • Focal nephritis can appear mass-like

    • Short term follow-up helpful

  • Clinical history and urine analysis often helpful

Metastatic Disease

  • History essential

  • Common primary cancers include lung, breast, colon, melanoma, pancreatic

  • Typically only hypervascular metastases mistaken for RCC


General Features

  • General path comments

    • Staging

      • Stage I: Solid mass ≤ 7 cm, confined to kidney

      • Stage II: > 7 cm but still organ confined; spread to perinephric fat

      • Stage III: Invasion of renal vein or vena cava, involvement of ipsilateral adrenal gland &/or perinephric fat, or spread to one local lymph node

      • Stage IV: Invasion of adjacent organs, more than one local node, or distant metastases

  • Genetics: Associated with von Hippel-Lindau syndrome (autosomal dominant)

  • Etiology

    • Arise from tubular epithelium

    • Bilateral lesions associated with von Hippel-Lindau syndrome, tuberous sclerosis, chronic dialysis

    • Other risk factors: Smoking, chemical exposure (diethylstilbestrol and fluoroacetamide)

  • Epidemiology

    • Approximately 2% of adult malignancies (30,000/year in USA)

    • Undiagnosed small RCCs found at autopsy even more frequently

Gross Pathologic & Surgical Features

  • Solid to cystic components with necrosis, hemorrhage, and rarely fat

Microscopic Features

  • 70% clear cell, 13% papillary, 7% granular, 10% other



  • Most common signs/symptoms

    • Usually a combination of hematuria (50%), flank pain (40%), &/or flank mass (35%)

    • Nearly half of RCCs discovered incidentally

  • Other signs/symptoms

    • Fever, nausea, weight loss

    • Rarely, humoral factors such as erythropoietin, renin, parathyroid hormone, or prolactin may cause symptoms


  • Age: Generally 50-70 years, with wide distribution

  • Gender: M > F, 2:1

Sep 22, 2016 | Posted by in MAGNETIC RESONANCE IMAGING | Comments Off on Renal Cell Carcinoma

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