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Flashcards in Pulmonary Pathology II Deck (22)
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Alveolar Septa (general definition) + pathology affecting alveolar septa

  • thin structure contain small blood vessels (capillaries) and lined by epithelial cells
  • Usual Interstitial Pneumonia (UIP)
  • NonSpecific Interstitial Pneumonia (NSIP)
  • Hypersensitivity Pneumonia (HP)


Pathologic (histologic) features of UIP

  • Patchy heterogeneous fibrosis of the septa by mature collagen
  • Fibroblastic foci (compact collections of fibroblasts and myxoid stroma buldging into the airspaces)
  • Honeycomb cystic change (end-stage lung remodeling with mucus filled cysts lined by airway-type epithelium and surrounded by fibrosis)


Pathologic (histologic) features of NSIP

  • Uniform homogenous inflammation, fibrosis or a mixture of both
  • Few if any fibroblastic foci
  • Little if any honeycombing 
  • cellular, fibrotic or mixed


Pathologic (histologic) features of HP

  • Airway-centered chronic inflammation (lymphocytes and histiocytes)
  • Nonnecrotizing granulomas
  • Focal organizing pneumonia
  • Variable fibrosis by mature collagen
  • A response to foreign antigens (birds, mold, hot-tub mycobacterial antigens, etc.)


Pathology that can affect pulmonary vessels

  • thromboembolic disease
  • talc embolism
  • pulmonary hypertension
  • vasculitis


Pathologic (histologic) changes in thromboembolic disease

  • Organizing fibrin clots within pulmonary arteries
  • May form in situ (thrombus) or move to the lung from elsewhere (embolism)


Pathologic (histologic) changes in talc embolism

  • Polarizable crystals around vessels
  • May include foreign-body giant cells
  • Usually from intravenous drug use


Pathologic (histologic) changes in pulmonary HTN

  • Muscular hypertrophy of pulmonary arteries
  • Muscularization of arterioles (normally should not contain smooth muscle)
  • Some forms have plexiform lesions (the artery lumen replaced by endothelial proliferation with numerous tangled slit-like lumens)


Pathologic (histologic) changes in vasculitis

  • Inflammation of the vessel wall
  • Often results in alveolar hemorrhage
  • May be autoimmune or infectious


Nodule-forming pathologies

  • sarcoid/chronic beryllium disease
  • pulmonary lagerhans' cell histiocytosis (PLCH)/Eosiniphillic Granuloma (EG)
  • carcinoid
  • small cell carcinoma
  • squamous cell carcinoma
  • adenocarcinoma
  • large cell carcinoma


Pathologic (histologic) of sarcoid/chronic beryllium disease

  • Well-formed coalescing nonnecrotizing granulomas (must exclude infection)
  • Variable concentric collagen deposition around granulomas
  • “lymphatic distribution” = found next to blood vessels, airways and in the pleura



Pathologic (histologic) of Pulmonary Langerhans’ Cell Histiocytosis (PLCH) / Eosinophilic Granuloma (EG)

  • Cellular phase
    • Langhans histiocytes 
    • Variable inflammation including eosinophils
  • Fibrotic/burnt-out phase 
    • Stellate scar around airway
  • Usually smoking-related if limited to lung


Pathologic (histologic) of Carcinoid nodules

  • Nests and ribbons of neuroendocrine cells with powdery salt-and-pepper chromatin
  • Stain positive for neuroendocrine markers (chromogranin, synaptophysin, CD56)
  • Usually indolent, but may act in a malignant fashion particularly if there is nuclear atypia, high mitotic rate or regions of necrosis


Pathologic (histologic) of small cell carcinoma

  • Small blue easily-crushed cells with scant cytoplasm
  • Stain positive for neuroendocrine markers (chromogranin, synaptophysin, CD56)
  • High mitotic rate and abundant necrosis


Pathologic (histologic) of squamous cell carcinoma

  • Large polygonal cells with hyperchromatic (dark) nuclei and abundant cytoplasm
  • Rarely have prominent nucleoli
  • May be keratinizing and form ‘keratin pearls’


Pathologic (histologic) of adenocarcinoma

  • Cells with large nuclei, large nucleoli and variable amounts of cytoplasm
  • Form gland-like structures
  • If cells only line the alveolar septa but do not invade, considered adenocarcinoma in situ (formally known as bronchioloalveolar cell carcinoma)


Pathologic (histologic) of large cell carcinoma

Large, sometimes bizarre-appearing, malignant cells that lack the typical features of either squamous cell carcinoma or adenocarcinoma


Histologic feature + associated dx

  • fibroblast foci
  • dx: UIP


Probable Dx

Fibrotic NSIP


Histologic finding + probable dx

  • plexiform lesion
  • dx: pulmonary hypertension


Histologic finding + probable dx

  • keratin pearl
  • dx: squamous cell carcinoma


Histologic finding + probable dx

  • gland-like structure
  • dx: adenocarcinoma