Pulmonary Calcification



Pulmonary Calcification


Jeffrey P. Kanne, MD



DIFFERENTIAL DIAGNOSIS


Common



  • Mycobacterial Pneumonia


  • Fungal, Histoplasmosis


Less Common



  • Hamartoma


  • Silicosis/Coal Worker’s Pneumoconiosis


  • Carcinoid


  • Lung Metastases


Rare but Important



  • Amyloidosis


  • Metastatic Pulmonary Calcification


  • Lung Ossification


  • Alveolar Microlithiasis


ESSENTIAL INFORMATION


Key Differential Diagnosis Issues



  • Nodules



    • Diffuse, central, lamellated, or “popcorn” pattern calcification in lung nodule usually reflects benign etiology


    • Eccentric or stippled calcification in lung nodule is indeterminate


Helpful Clues for Common Diagnoses



  • Mycobacterial Pneumonia



    • Most common cause of granulomatous infection worldwide


    • Calcified lung nodule indicates healed disease with fibrosis and dystrophic calcification


    • Calcifications in ipsilateral hilar and mediastinal lymph nodes frequent


  • Fungal, Histoplasmosis



    • Endemic fungus commonly encountered in Ohio and Mississippi river valleys


    • Calcified lung nodule indicates healed disease with fibrosis and dystrophic calcification



      • Indistinguishable on imaging from healed mycobacterial infection


    • Splenic calcifications more common and more numerous with histoplasmosis than mycobacterial disease


Helpful Clues for Less Common Diagnoses



  • Hamartoma



    • Most common benign lung neoplasm



      • 8% of all primary lung tumors


    • Vast majority (˜ 95%) occur in lung parenchyma


    • ˜ 5% hamartomas endobronchial


    • Chest radiograph



      • Well-circumscribed lung nodule with smooth margins


      • Calcification apparent in 10%


      • Most < 4 cm in diameter


    • CT



      • Approximately 2/3 contain focal fat attenuation, which is diagnostic


      • Coarse “popcorn” calcification in nodule suggestive but uncommon


      • Endobronchial hamartomas usually associated with obstructive pneumonia or atelectasis


  • Silicosis/Coal Worker’s Pneumoconiosis



    • Exposure to free silica (silicosis) or coal dust (CWP)


    • Usually develops after 20 years of exposure


    • Silicosis and CWP indistinguishable radiographically


    • Chest radiograph and CT



      • Small (3-6 mm) round, well-defined calcified or noncalcified nodules


      • Upper lobe, posterior predominance


      • Perilymphatic distribution (CT)


      • Mediastinal and hilar lymphadenopathy in up to 40% (˜ 50% with calcification)


  • Carcinoid



    • 1-2% of all pulmonary neoplasms


    • < 5% have visible calcification on chest radiograph


    • Calcification present in ˜ 30% on CT



      • More common with central than peripheral carcinoid tumors


      • Pattern of calcification is variable


      • Can diffusely calcify and mimic a broncholith


  • Lung Metastases



    • Sarcomas (most common), especially chondrosarcoma, osteosarcoma, and synovial cell sarcoma


    • Mucinous adenocarcinomas (digestive tract, breast, ovarian)


    • Medullary thyroid carcinoma (uncommon)


Helpful Clues for Rare Diagnoses



  • Amyloidosis



    • Accumulation of insoluble protein in extracellular space



    • Can be limited to lungs (most common) or part of systemic disease, such as multiple myeloma


    • Nodular parenchymal most common pattern of pulmonary amyloidosis



      • Solitary nodule more common than multiple nodules


      • Nodules usually range from 5-50 mm in diameter


      • Occasional large mass


      • Calcification rarely apparent on chest radiograph


      • Up to 50% have calcification on CT


  • Metastatic Pulmonary Calcification



    • Occurs from hypercalcemia, most frequently from chronic renal failure


    • Chest radiograph usually normal but may show fluffy nodule or patchy lung consolidation



      • Upper lobes mainly affected


    • CT findings include poorly defined, centrilobular nodules with upper lobe predominance



      • 3-10 mm in diameter


      • Calcification may be diffuse, stippled, or circumferential


      • Calcification may not be apparent on CT


    • Lung parenchyma may take up radiotracer on bone scan


  • Lung Ossification



    • Characterized by metaplastic bone formation in lung parenchyma


    • 2 patterns: Nodular and dendriform



      • Nodular pattern most common with longstanding mitral valve stenosis


      • Dendriform pattern associated with chronic inflammation and interstitial fibrosis


      • CT shows calcification better than chest radiography


    • Can be confused with metastatic calcification


  • Alveolar Microlithiasis

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Aug 8, 2016 | Posted by in CARDIOLOGY | Comments Off on Pulmonary Calcification

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