Chapter 22 - Lungs Flashcards
What are the four principal components of the lungs?
Large airways (bronchi)
Small airways & air spaces (bronchioles & alveoli)
Interstitium
Vessels
Describe the morphologic appearance of bronchi.
Ciliated or columnar epithelium with goblet cells. Goblet cell metaplasia can indicate irritation, as can squamous cell metaplasia.
Also note seromucinous glands, cartilage, smooth muscle, and bronchial arteries.
Describe the morphologic appearance of bronchioles.
Cuboidal epithelium without goblet cells.
Clara cells, which are difficult to see.
No cartilage.
Describe the morphologic appearance of alveoli.
Thin walls lined by flat type I epithelium. Alveolar macrophages scattered throughout.
Cuboidal epithelium indicates type II hyperplasia, seen in inflammation/repair.
Describe the morphologic appearance of vessels
Pulmonary arterioles: Run with bronchioles, two elastic layers on Movats stain.
Veins: Run in interlobular septa, one irregular elastic lamina.
Lymphatics: Run with arteries, veins, and in pleura.
What is Movats stain, and what does it paint?
A supplemental stain for fibrotic lung.
Elastic laminae - Black
Hyaluronic acid - Aqua blue
Mature collagen - Yellow
Smooth muscle - Dull red
Fibrinoid necrosis - Bright red
What are the three phases of injury response in lung?
Acute, subacute, chronic
How does acute lung injury manifest?
What is acute interstitial pneumonitis, and how does it appear?
As diffuse alveolar damage.
AIP has no identifiable factor. It features interstitial edema/hemorrhage, hyaline membrane formation, type II hyperplasia, and fibrin thrombi.
How does subacute lung injury manifest?
Fibroblast foci form in alveoli and bronchioles. This is indistinguishable from BOOP.
How does chronic lung injury manifest?
With end fibrosis and honeycomb lung. “Usual interstitial pneumonia” is the nonspecific pattern, and is called “idiopathic pulmonary fibrosis” when no etiology is known.
Describe the appearance of usual interstitial pneumonia.
Temporal heterogeneity; meaning seeing acute / subacute / chronic injury in the same tissue.
Prominent interstitial fibrosis, distortion of airspaces, with fibroblast foci, acute & chronic inflammation.
What are the two forms of allergic lung disease, and what are some examples?
IgE-mediated: Asthma, ABPD, eosinophilic pneumonias
Cell-mediated hypersensitivity: Pneumonconioses, patchy chronic interstitial pneumonia, foci of BOOP.
What lung disease patterns are seen in smokers?
DIP (desquamative interstitial pneumonitis)
Respiratory bronchiolitis
Langerhans cell histiocytosis
Usual interstitial pneumonia
Obstructive lung diseases: Emphysema and chronic bronchitis
What is DIP?
Desquamative interstitial pneumonitis
Alveolar macrophages pack the alveoli, usually in smokers but in other disease processes as well.
How does langerhans cell histiocytosis appear?
Why is this in the lung chapter?
Collections of histiocytes (pale nuclei with folds and creases), sometimes with eosinophils (“eosinophilic granuloma”).
Half of cases occur in adults, generally as isolated pulmonary diseases of smokers.
What two epithelia do lung cancers arise from?
Respiratory epithelium
Squamous metaplastic epithelium
What is atypical adenomatoid hyperplasia, and how does it appear?
A small focus (~1cm) of type II hyperplasia, which is plump cuboidal to columnar eosinophilic. This is probably a dysplastic lesion and results from chronic irritation.
Describe the appearance and location of squamous carcinoma.
Usually keratinizing with dense pink cytoplasm, keratin whorls, and distinct cell borders.
Arises from squamous metaplasia, usually in the major bronchi. Therefore, it is central or hilar.
How is squamous carcinoma graded?
Name six variants.
Well / Moderately / Poorly differentiated
Nonkeratinizing, basaloid, small cell (no neuroendocrine stainin!), spindle cell, clear cell, intrabronchial papillary
What are the types and patterns of lung adenocarcinoma?
Acinar, tubular, papillary, solid. Lepidic?
Can be mucinous or nonmucinous.
Describe the appearance of bronchioalveolar carcinoma.
Columnar and usually eosinophilic cells outlining the air spaces. Can be mucinous or nonmucinous.
Note: Do not call unless lesion is ENTIRELY sampled.
What is large cell undifferentiated carcinoma?
Lymphoepithelioma-like carcinoma?
Large cell: Undifferentiated with ugly appearance and no recognizable features. Can be giant cell.
Lymphoepithelioma-like: Scattered large malignant cells in a sea of lymphocytes.
Describe and contrast carcinoid and atypical carcinoid tumors.
Carcinoid: Well-differentiated neoplasm with classic neuroendocrine features. Can metastasize to lymph nodes.
Atypical carcinoid: Increased mitoses (2-10/10hpf), hyperchromatic nuclei, and/or necrosis.
Describe small cell neuroendocrine carcinoma of the lung.
High-grade neoplasm with small cell morphology, hyperchromatic nuclei, no nucleoli. Syncytial appearance with nuclear molding, crush artifact.
Describe large cell neuroendocrine tumor.
A high-grade neuroendocrine neoplasm, with large cytoplasm. Neuroendocrine features can be architectural or nuclear, but staining should be positive.
What is non-small cell carcinoma with neuroendocrine features?
A tumor that looks like NSCLC but is chromogranin-positive.
What is a hamartoma?
Tumor-like mass composed of mixture of normal organ elements (usually cartilage, fat, smooth muscle, and epithelium)
Describe carcinosarcoma of lung.
A biphasic lesion, with a carcinoma and usually an osteosarcoma or chondrosarcoma.
What is pulmonary blastoma?
Pleuropulmonary blastoma?
Pulmonary blastoma: A form of carcinosarcoma in adults. Epithelial component resembles fetal lung, stromal component may be adult-type or immature mesenchyme.
Pleuropulmonary blastoma: Embryonal-type sarcoma of infancy which has only cartilage and/or rhabdomyoblastic elements (no carcinoma)
Normal bronchus
- Ciliated columnar epithelium
- Goblet cells
- Cartilage
- Smooth muscle
- Bronchial artery branches
Bronchioles & alveoli
B: Bronchiole, lined by cuboidal epithelium and smooth muscle.
A: Arteriole
V: Venule, running in septa
Arrow: Alveolar walls
Arrowhead: Alveolar macrohpages
Movats stain of lung.
A: Artery with two elastic laminae (arrowheads)
V: Vein with one elastic lamina (arrow)
Diffuse alveolar damage.
Asterisk: Fluid and blood in interstitial spaces
Arrow: Thick pink hyaline membranes
Fibroblast foci
Left: On H&E, they appear myxoid and pale
RIght: On Movats, they appear turquoise
Usual interstitial pneumonia
Arrowhead: Interstitial thickening & fibrosis
Arrow: Chronic inflammation
Inset: Irregularly shaped alveolar spaces with type II hyperplasia.
Reactive epithelium overlying a carcinoid tumor.
Arrow: Note presence of cilia, marking benign epithelium
Atypical adenomatoid hyperplasia
Arrow: Interstitial inflammation
Arrowhead: Type II hyperplasia
Squamous cell carcinoma
Left: Moderately differentiated, with bright dense pink cytoplasm (arrow).
Right: Basaloid squamous cell carcinoma, with rounded nests of blue tumor cells and central necrosis (asterisk).
Sarcomatoid carcinoma. Note sheets of spindled cells with prominent nucleoli.
Arrow: Mitoses
Lung adenocarcinoma.
Arrow: Cribriforming
Arrowhead: Small glands in a desmoplastic stroma
Bronchoalveolar carcinoma
Note lining of the air spaces with malignant cells but with no invasion or mass effect.
Carcinoid tumor
Note nested & trabecular pattern of cells with neuroendocrine chromatin (speckled, without nucleoli)
Small cell carcinoma
Note nuclear molding and crowded cells with little cytoplasm. Neuroendocrine nuclei. Necrosis and mitoses (arrow) are common.
