Renopulmonary Syndromes

Jud W. Gurney, MD, FACR

DIFFERENTIAL DIAGNOSIS

Common

Uremic Pulmonary Edema
Uremic Pericarditis
Diffuse Alveolar Hemorrhage (DAH)
- Wegener Granulomatosis
- Goodpasture Syndrome
- Systemic Lupus Erythematosus
- Microscopic Polyangiitis
Renal Cell Carcinoma

Less Common

Lymphangiomyomatosis
Metastatic Pulmonary Calcification
Sarcoidosis

Rare but Important

Sickle Cell Disease
Birt-Hogg-Dubé Syndrome
Erdheim Chester Disease

ESSENTIAL INFORMATION

Key Differential Diagnosis Issues

Recognition of renal osteodystrophy in chronic renal failure (CRF)
- Bone resorption
  - Erosion of distal clavicles
- Osteopenia (50%)
  - Compression fractures (5-25%)
  - Rib fractures (5-25%)
- Osteosclerosis of axial skeleton (10-30%)
  - Vertebral bodies: Band-like areas of sclerosis of superior and inferior endplates (“rugger jersey” spine)
- Brown tumors (1%): Lytic expansile lesions, cortical, usually solitary
- Soft tissue calcification
  - Periarticular and symmetric
Pleural effusions common in CRF
- From overhydration, left ventricular (LV) failure, nephrotic syndrome, autoimmune disease, peritoneal dialysis
Cardiomegaly common in CRF
- From overhydration, LV failure, high output failure, pericardial disease, underlying disease causing renal failure

Helpful Clues for Common Diagnoses

Uremic Pulmonary Edema
- Batwing central pulmonary opacities classic but not specific
- From LV failure, overhydration, anemia, hypoproteinemia, high output AV fistula, diffuse alveolar damage (uremic lung)
Uremic Pericarditis
- Includes acute pericarditis, pericardial effusions, cardiac tamponade, constrictive pericarditis
- Injury from toxic metabolites from renal failure, underlying disease, drug toxicity
- Cardiomegaly in 95%
Diffuse Alveolar Hemorrhage (DAH)
- From small-vessel vasculitis affecting lung and kidney
- Acute onset batwing consolidation in anemic patient
- Hemoptysis (66%), may be mild
- Radiology-pathology correlation
  - Hemorrhage into alveolar spaces (ground-glass opacities to consolidation)
  - Blood removed from alveoli by macrophages (2-3 days)
  - Macrophages migrate into interstitium (septal thickening)
  - Macrophages removed by lymphatics (7-14 days) (lungs return to normal)
- Wegener Granulomatosis
  - Hemorrhagic presentation in 8%
  - May occur in absence of cavitary nodules
- Goodpasture Syndrome
  - May follow influenza-type illness
  - Males (M:F = 9:1), often smokers
- Systemic Lupus Erythematosus
  - Autoimmune disorder characterized by antinuclear antibodies, females (M:F = 1:10)
  - Hemorrhage in 2%, may be fatal
  - Renal involvement in 60-90%
  - Unexplained small bilateral pleural effusions and cardiomegaly
- Microscopic Polyangiitis
  - Variant of polyarteritis nodosa
  - Pulmonary hemorrhage (10-30%)
  - Glomerulonephritis (80-100%)
Renal Cell Carcinoma
- Propensity for metastasizing to uncommon locations (e.g., mediastinal nodes, endobronchial, intravascular) in addition to typical locations (lung, pleura, bone)

Helpful Clues for Less Common Diagnoses

Lymphangiomyomatosis
- Nonneoplastic hamartomatous proliferation of atypical muscle cells
- Women of child-bearing age
- Radiographic manifestations
  - Thin-walled cysts: Diffuse, bilateral, and uniform in size; cysts increase in number and size as disease progresses, results in hyperinflation
  - Spontaneous pneumothorax (40%)
  - Small chylous pleural effusions
- Renal angiomyolipomas (20-50%): Small (< 1 cm), multiple, bilateral
Metastatic Pulmonary Calcification
- Calcium deposition in normal tissue
- Tropism for tissues with relative alkaline pH: Upper lung zones, gastric wall, kidney medulla
- Due to hypercalcemic condition, most commonly chronic renal failure
- HRCT: Mulberry-shaped nodules of amorphous calcification 3-10 mm in diameter in centrilobular location
Sarcoidosis
- 3.5% develop nephrolithiasis, may be presenting feature
- Hypercalciuria (50%), hypercalcemia (20%)
- Pulmonary macrophages produce calcitriol
- Stones more common in sunny months

Helpful Clues for Rare Diagnoses

Sickle Cell Disease
- Due to abnormal hemoglobin, which deforms when deoxygenated
- Nephropathies: Papillary necrosis, renal infarcts, pyelonephritis, renal medullary carcinoma
- Radiographic manifestations
  - Lungs: Variable-sized opacities due to pneumonia, atelectasis, or infarcts; interstitial thickening from edema
  - Cardiac: Cardiomegaly
  - Skeletal: Osteonecrosis of humeral heads, H-shaped vertebra (10%), enlarged ribs (marrow expansion), bone sclerosis (bone infarcts)
  - Abdomen: Small or absent spleen
Birt-Hogg-Dubé Syndrome
- Facial papules (fibrofolliculomas)
- Renal tumors: Range from oncocytomas to renal cell carcinoma
  - May be bilateral and multifocal
- Lungs: Thin-walled cysts, predominantly lower lobes, few in number
  - Lung cysts closely associated with interlobular septa or visceral pleura
Erdheim Chester Disease
- Non-Langerhans cell histiocytosis
- Skeletal: Bilateral symmetric osteosclerosis of metaphyses and diaphyses, especially long leg bones (sparing epiphyses)
- Renal: Perirenal fat effaced by soft tissue, bilateral and symmetric
- Lungs and pleura: Smooth thickening of visceral pleura and fissures, usually bilateral and symmetric
- Cardiac: Cardiac enlargement from pericardial or cardiac involvement

Image Gallery

Frontal radiograph shows central batwing consolidation

. Edema is most common, but differential includes hemorrhage and infection. Other patterns of edema are common.

Frontal radiograph shows mild cardiomegaly

. Cardiomegaly is common with renal disease and may be due to left ventricular failure, pericarditis, or secondary to underlying disease.

(Left) Axial CECT shows moderate pericardial effusion

. Tubular shape of the right ventricle

suggests mild constriction or tamponade. Pericardial disease may be secondary to uremic toxins, underlying disease (like SLE), or drugs used to treat underlying disease. (Right) Axial CECT shows multiple foci of pericardial calcification