Thursday, September 14, 2017

Thoracic Masses and Malignancies

This post is derived from notes I took during training. Any images are copyright their respective owners.


  • Solitary pulmonary nodule (SPN)
    • Defined as a lesion < 3 cm, considered benign if stable for 2 years
    • 50% benign, 40% primary lung cancer, 10% metastasis
    • Signs of benignity
      • Fat
      • Doubling time <1 mo="" or="">16 months
      • Calcification
    • PET-CT avid nodules are much more likely to be malignant, although active granulomatous disease can create false positive.  Bronchoalveolar carcinoma (BAC) or carcinoid may create false negative.
  • Hamartoma
    • Gender ratio M:F 2:3, most asymptomatic
    • Benign mass of mesenchymal origin (possibly chromosome 12), containing fat and calcification if degenerating (popcorn pattern)

  • Small cell lung carcinoma
    • 20% of all lung cancer. Central, rapid growth, early metastasis.
    • Associated with Eaton-Lambert syndrome (proximal muscle weakness), paraneoplastic Cushing's syndrome, SIADH
  • Adenocarcinoma in situ (Bronchoalveolar carcinoma)
    • Peripheral
    • FDG poor so not well seen on PET
    • Bronchogenic cancer often spreads to adrenal glands
  • Synchronous cancers - two separate primaries detected within 6 months of each other without metastases
  • Metachronous cancers - two separate primaries diagnosed at separate times without metastases.
  • Lymphangitic carcinomatosis - reticulonodular opacities, septal lines, mediastinal/hilar lymphadenopathy
  • Inflammatory pseudotumor (inflammatory myofibroblastic tumor) - rare, invasive
  • Solitary fibrous tumor of pleura - associated with hypoglycemia and fibrous hypertrophic osteoarthropathy
  • Superior sulcus (Pancoast) tumor - associated with brachial plexopathy, pupillary / Horner's syndrome triad (ptosis (lid dropping), miosis (pupillary constriction), anhidrosis (loss of sweating))
  • Radiation pneumonitis
    • Acute: 1-3 months post treatment, patchy ground glass opacities, lucencies, volume loss
    • Chronic: 6-12 months, consolidation, traction bronchiectasis, volume loss



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