II. Epidemiology

  1. Incidental Renal Mass on Autopsy (over age 50): 50%
  2. Incidental Renal Mass on CT Scan (over age 50): 33%

III. Differential Diagnosis

  1. Renal Cyst (Simple, Complex or Multiple)
  2. Malignant Masses
    1. Renal Cell Carcinoma
    2. Lymphoma
    3. Sarcoma
    4. Metastatic cancer
  3. Benign Masses
    1. Renal adenoma
    2. Angiomyolipoma
    3. Oncocytoma
  4. Inflammatory Lesions
    1. Renal infection
    2. Renal infarction
    3. Renal Trauma (hematoma)

IV. Imaging: Management of Mass on Renal Ultrasound

  1. Efficacy
    1. Test Sensitivity: 79% of renal parenchymal masses
    2. Does not detect Renal Masses less than 5 mm diameter
  2. Simple Renal Cyst Criteria
    1. Spherical or ovoid shaped cysts
    2. No internal echoes
    3. Thin smooth cyst wall separated from renal parenchyma
    4. Posterior cyst wall enhancement
      1. Suggests water-filled cyst
  3. Management
    1. Simple cysts require no further evaluation
    2. Abdominal CT or MRI indicated for other masses

V. Imaging: Management of Mass on Renal CT

  1. Efficacy
    1. Test Sensitivity: 94% of renal parenchymal masses
    2. MRI better distinguishes benign Renal Masses
  2. Absolute Surgery Consultation Indications
    1. Symptomatic Renal Mass
    2. Solid Renal Mass
    3. Bosniak Class III-IV Cystic Mass (see below)

VI. Imaging: Asymptomatic Renal Mass on Renal CT

  1. Bosniak's Class I: Simple Cystic Renal Mass
    1. Criteria
      1. See Renal Ultrasound Criteria above
      2. Round or oval shape
      3. Unilocular with uniform water density within
      4. No contrast enhancement
    2. Management
      1. Observe
      2. Repeat imaging if symptomatic
  2. Bosniak's Class II Probably Benign Cystic Renal Mass
    1. Criteria
      1. Septated cysts
      2. Minimally calcified cysts
      3. Infected cysts
      4. High-density cysts
    2. Management
      1. Repeat Renal CT in 6 to 12 months
  3. Bosniak's Class III Indeterminate Cystic Renal Mass
    1. Criteria
      1. Thick irregular calcifications
      2. Irregular borders
      3. Multilocular
      4. Thickened or contrast enhancing septae
      5. Uniform wall thickening
      6. Small, non-contrast enhancing Nodules
    2. Management
      1. Renal CT or MRI
      2. Surgery Consultation
  4. Bosniak's Class IV Malignant Cystic Renal Mass
    1. Criteria
      1. Heterogeneous lesions with shaggy appearance
      2. Thickened cyst walls
      3. Contrast enhancing Nodules
    2. Management
      1. Renal CT or MRI
      2. Surgery Consultation

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Ontology: Renal mass (C0262613)

Concepts Finding (T033)
SnomedCT 309088003
Italian Massa renale, Massa renale NAS
Dutch niergezwel NAO, massa; nier, nier; massa, niergezwel
French Masse rénale SAI, Masse rénale
German Raumforderung Niere NNB, Raumforderung Niere
Portuguese Massa renal NE, Massa renal
Spanish Masa renal NEOM, masa renal (hallazgo), masa renal, Masa renal
Japanese 腎腫瘤, 腎腫瘤NOS, ジンシュリュウ, ジンシュリュウNOS
Czech Renální rezistence NOS, Renální rezistence
English kidney masses, kidney mass, kidneys mass, mass kidney, mass renal, masses renal, renal mass, Renal mass NOS, Kidney mass, Renal mass, Renal mass (finding), kidney; mass, mass; kidney, Kidney Mass, Renal Mass
Hungarian vese térfoglaló folyamata, vese térfoglaló folyamata k.m.n.