Pulmonary Pathology II Flashcards
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
