Idiopathic Pulmonary Fibrosis
Progressive exertional dyspnea, dry cough, bilateral bibasilar end-inspiratory Velcro crackles, and peripheral subpleural honeycombing on HRCT.
Sarcoidosis Hallmark
Non-caseating granulomas in young African-American females; bilateral hilar lymphadenopathy on CXR, elevated ACE, hypercalcemia, erythema nodosum.
Light's Criteria (Exudate)
Pleural/serum protein > 0.5, Pleural/serum LDH > 0.6, or Pleural LDH > 2/3 upper limit of normal serum LDH; indicates local infection or malignancy.
Tension Pneumothorax
Hypotension, distended neck veins, absent breath sounds on affected side, tracheal deviation AWAY from affected side; emergent needle decompression.
Interstitial Lung Diseases: IPF vs. Sarcoidosis vs. Pneumoconioses
| Disease | Key Patient Demographics | Imaging & Histopathology | Diagnostic & Treatment Hallmark |
|---|---|---|---|
| Idiopathic Pulmonary Fibrosis (IPF) | Men > 60 years old; progressive dyspnea and dry cough | HRCT: Honeycombing, traction bronchiectasis, subpleural reticulation in lung bases | Usual Interstitial Pneumonia (UIP) pattern; Antifibrotic therapy (Pirfenidone, Nintedanib); lung transplant |
| Sarcoidosis | Young adults (20–40), disproportionately African-American women | CXR: Bilateral hilar lymphadenopathy; Biopsy: Non-caseating granulomas (negative for AFB/fungi) | Elevated serum ACE, hypercalcemia (macrophage 1-alpha-hydroxylase producing 1,25-OH2 vitamin D); systemic corticosteroids |
| Asbestosis | Shipbuilding, insulation, demolition, roofing workers | CXR: Pleural plaques along diaphragm/lower lobes; Ferruginous bodies (Prussian blue stain) | Predisposes to Bronchogenic carcinoma >> Malignant Mesothelioma (calretinin positive) |
| Silicosis | Sandblasting, foundry work, stone cutting, mining | CXR: Eggshell calcification of hilar lymph nodes; upper lobe nodules | Disrupts phagolysosomes in alveolar macrophages; increased susceptibility to active Tuberculosis |
Pleural Effusion Triage: Transudate vs. Exudate
| Effusion Category | Underlying Pathophysiologic Mechanism | Common Etiologies | Pleural Fluid Chemistry |
|---|---|---|---|
| Transudative Effusion | Imbalance between hydrostatic and oncotic pressures; capillary integrity intact | Heart failure (most common), Cirrhosis (hepatic hydrothorax), Nephrotic syndrome | Fails all Light's criteria: Pleural/Serum Protein ≤ 0.5, Pleural/Serum LDH ≤ 0.6, Pleural LDH ≤ 2/3 ULN |
| Exudative Effusion | Increased vascular permeability and pleural inflammation | Parapneumonic effusion / Empyema, Malignancy, Pulmonary embolism, Tuberculosis, Rheumatoid arthritis | Meets ≥ 1 of Light's criteria; pH < 7.20 or glucose < 60 mg/dL mandates chest tube drainage |
OMM Board Correlate: Diaphragmatic Excursion & Rib Compliance
- Diaphragmatic Resynchronization: Dome and crura of the diaphragm attach to ribs 7–12 and L1–L3. Direct myofascial dome release improves transpulmonary pressure gradients.
- Lymphatic Outflow Obstruction: Over 80% of all pleural fluid resents into the parietal pleural lymphatic stomas. Decompressing the thoracic inlet (clavicle, subclavius, 1st rib) optimizes lymphatic drainage.
Board Traps & Common Distractors
- In Tension Pneumothorax, NEVER wait for a chest X-ray; immediate needle decompression (14-gauge angiocatheter in 2nd intercostal space midclavicular or 5th intercostal space midaxillary) followed by tube thoracostomy is life-saving.
- Small Cell Lung Cancer (SCLC) is a neuroendocrine malignancy (chromogranin/synaptophysin positive) strongly associated with smoking; highly prone to Paraneoplastic Syndromes: SIADH (hyponatremia), Cushing (ectopic ACTH), and Lambert-Eaton Myasthenic Syndrome.
- A complicated parapneumonic effusion or empyema with pleural fluid pH < 7.20, glucose < 60 mg/dL, or frank pus/bacteria on Gram stain requires immediate tube thoracostomy drainage; antibiotics alone will fail.