Lung

Question 1

small cell lung cancer (SCLC).

Answer 1

• presents as a hilar mass in patients with a significant smoking history, is the most common cause of ectopic secretion of ADH.
• patient’s hyponatremia is most likely due to syndrome of inappropriate antidiuretic hormone (SIADH), which is one of several paraneoplastic syndromes
• Presenting symptoms of SIADH are often vague (eg, lethargy), but untreated SIADH can lead to significant hyponatremia causing seizures or coma.
• Physical examination should reveal euvolemia, and laboratory results should demonstrate decreased serum osmolality consistent with true (hypotonic) hyponatremia

urine osmolality >100 mOsm/kg H2O, which reflects inability of the kidneys to produce adequately dilute urine to remove excess free water from the body (due to inappropriately high levels of ADH).

excessive release of ADH from the posterior pituitary (eg, central nervous system disorder, medication adverse effect) or ectopic secretion of ADH.

Question 2

Carcinoids

Answer 2

rare neuroendocrine tumors that typically occur in the digestive tract or lungs.
- lead to carcinoid syndrome (eg, flushing, diarrhea, bronchoconstriction), which is a paraneoplastic syndrome caused by secretion of serotonin, histamine, and kinins.

Question 3

Lung adenocarcinoma

Answer 3

cause paraneoplastic hypertrophic osteoarthropathy,

Question 4

squamous cell carcinoma

Answer 4

lead to paraneoplastic hypercalcemia (due to tumor secretion of parathyroid hormone-related protein

Question 5

Mesothelioma

Answer 5

rare malignancy derived from the mesothelial lining of the thoracic cavity and has been associated with a variety of paraneoplastic syndromes (eg, peripheral neuropathy, migratory thrombophlebitis).

Question 6

pulmonary emboli.

Answer 6

• multiple wedge-shaped hemorrhagic lesions in the periphery of the lung,
• Because there is dual blood supply to the lungs (eg, pulmonary and bronchial arteries), patients with pulmonary emboli typically develop hemorrhagic infarction as opposed to ischemic infarction.
• recent history of intravenous drug use and acute presentation with septic shock (eg, fever, tachycardia, tachypnea, hypotension) most likely developed septic pulmonary emboli from tricuspid valve endocarditis.
• Intravenous drug users are at increased risk for bacterial endocarditis involving the right-sided heart valves.
• Staphylococcus aureus is the most common pathogen responsible for infective endocarditis in these patients.

Question 7

Miliary tuberculosis

Answer 7

subacute or chronic presentation and is accompanied by night sweats, weight loss, and anorexia

Question 8

asthma

Answer 8

• Small airway obstruction - presents with dyspnea, cough, wheezing, and chest tightness.
• Lung autopsy usually reveals the occlusion of bronchi and bronchioles by thick mucous plugs containing shed epithelium.

Question 9

Venous thromboembolism to the pulmonary vasculature

Answer 9

lead to wedge-shaped hemorrhagic lesions in the periphery of the lung
- risk factors: prolonged immobility, hypercoagulable state)

Question 10

aspiration pneumonia

Answer 10

• develops in the most dependent portions of the lung
• Patients who aspirate while lying supine typically have involvement of the posterior segments of the upper lobes and the superior segments of the lower lobes
• right main bronchus is more prone to aspiration than the left main bronchus because it has a larger diameter, is shorter, and is more verti cally oriented than the left main bronchus
• mnemonic: “Swallow a bite, goes down the right”).

Patients who aspirate in upright (or semi-recumbent) positions tend to aspirate into the basilar segments of the lower lobes

Question 11

Asbestosis.

Answer 11

• pleural thickening with calcification of the posterolateral midlung zones
• calcified lesions (pleural plaques) are one of the hallmarks of asbestos exposure and usually affect the parietal pleura, especially between the 6th and 9th ribs.
• Benign pleural effusions can also occur
• Many patients are asymptomatic despite visible disease on imaging
• there is commonly a 20- to 30-year latency between asbestos exposure and onset of symptoms.
• some pxs develop full blown asbestosis which presents with slowly progressive diffuse pulmo fibrosis
• interstitial lung injury d/t fiber inhalataion predominatly affects thr lower pulmonary zones and manifests radiographically as linear interstitial densities

Question 12

Pulmonary berylliosis

Answer 12

resembles sarcoidosis (nodular infiltrates, enlarged lymph nodes, noncaseating granulomas

Question 13

Coal worker’s pneumoconiosis

Answer 13

presents radiologically as multiple discrete nodules (1-4 mm), most prominent in the upper lung zones.

Question 14

Nitrogen dioxide (NO2) is a toxic product of combustion,

Answer 14

which places firefighters, welders, and farm silo workers at risk.

-Patients have a presentation similar to asthma or chronic obstructive pulmonary disease and imaging may reveal pulmonary edema.

Question 15

Hypersensitivity pneumonitis

Answer 15

due to inhalation of organic dusts tends to result in diffuse nodular interstitial infiltrates on chest x-ray.

Question 16

pulmonary silicosis

Answer 16

Nodular densities and eggshell calcifications of the hilar nodes are seen.

Question 17

high-altitude sickness

Answer 17

• condition occurring as a result of low partial pressure of oxygen (pO2) in environments >2,500 m (8,000 ft).
• Common symptoms include headache, fatigue, nausea, dizziness, and sleep disturbances.
• Most cases subside within 2 days, but progression to life-threatening cerebral and/or pulmonary edema is possible.

pathophysiologic mechanism behind high-altitude sickness is hypobaric hypoxia

• Although the fraction of oxygen in inspired air remains constant at different terrestrial elevations, barometric pressure drops with increasing altitude, leading to decreased pO2 in the air and blood.
• resulting tissue hypoxia stimulates peripheral chemoreceptors, causing hyperventilation in an attempt to improve oxygenation.

results in decreased partial pressure of carbon dioxide (pCO2) and increased blood pH (respiratory alkalosis).

Renal bicarbonate excretion compensates for the alkalosis, stabilizing the pH toward the normal range within 48 hours.

Question 18

Adenocarcinoma in situ (formerly known as bronchioloalveolar carcinoma)

Answer 18

• one of the major subtypes of lung adenocarcinoma, the most common type of lung cancer in the United States.
• arises from the alveolar epithelium and is located at the periphery of the lung.
• considered a preinvasive lesion characterized by growth along intact alveolar septa without vascular or stromal invasion.
• Microscopic examination reveals well-differentiated, dysplastic columnar cells with or without intracellular mucin (compare to normal lung).
• The tumor has a tendency to undergo aerogenous spread (along the airways) and can progress to invasive disease if not resected.
• Mucinous forms can also result in the production of copious amounts of watery sputum (bronchorrhea). Imaging shows a discrete mass or pneumonia-like consolidation.

Question 19

Atypical pneumonia

Answer 19

caused by Mycoplasma pneumoniae and typically affects younger patients (eg, children, military recruits, college students).

• seen on chest x-ray as an area of patchy infiltration.
• Light microscopy will show an inflammatory infiltrate involving the trachea, bronchioles, and peribronchial interstitium.

Question 20

Hamartomas

Answer 20

• benign lung tumors that are often detected incidentally on chest x-ray as a peripheral “coin lesion.”
• ## Histological examination shows areas of mature hyaline cartilage mixed with connective tissue, smooth muscle, and fat.

Question 21

Pulmonary infarction

Answer 21

caused by pulmonary artery embolism. Symptoms include dyspnea, cough, and chest pain. A hemorrhagic (red) infarct is seen on light microscopy.