Pulmonology · Interstitial Lung Disease
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Idiopathic pulmonary fibrosis presents clinically as a progressive exertional dyspnea and a chronic nonproductive cough in older adults.
Physical examination classically reveals bilateral end-inspiratory fine crackles described as Velcro-like rales at the lung bases.
High-resolution computed tomography (HRCT) is the diagnostic gold standard, demonstrating subpleural, basal-predominant reticular opacities and honeycombing.
Pulmonary function testing typically demonstrates a restrictive pattern characterized by decreased total lung capacity (TLC) and a reduced diffusing capacity for carbon monoxide (DLCO).
Histopathology of the lung tissue shows the hallmark pattern of usual interstitial pneumonia (UIP), characterized by temporal heterogeneity with areas of normal lung, fibrosis, and fibroblastic foci.
The disease is a diagnosis of exclusion, requiring the clinician to rule out connective tissue diseases, environmental exposures, and drug-induced interstitial lung disease.
First-line pharmacologic management to slow disease progression includes the antifibrotic agents nintedanib or pirfenidone.
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A 68-year-old male presents to the clinic with a 10-month history of progressive shortness of breath and a dry cough. He has no history of smoking or occupational dust exposure. On physical exam, he has clubbing of the digits and bilateral end-inspiratory fine crackles at the lung bases. Pulmonary function tests show a decreased FVC and a reduced DLCO with a preserved FEV1/FVC ratio. HRCT of the chest reveals subpleural reticular opacities and honeycombing in the lower lobes.
What is the most likely diagnosis?
Idiopathic pulmonary fibrosis
The patient's presentation of progressive dyspnea, Velcro-like crackles, and the classic HRCT findings of honeycombing and subpleural reticulation are diagnostic of idiopathic pulmonary fibrosis, which is confirmed by the UIP pattern on imaging.
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Etiology / Epidemiology
Occurs primarily in males > 50 years old with a history of smoking or environmental exposure.
Clinical Manifestations
Presents with progressive exertional dyspnea and Velcro-like bibasilar inspiratory crackles.
Diagnosis
High-resolution CT (HRCT) showing usual interstitial pneumonia (UIP) pattern is diagnostic.
Treatment
Nintedanib or Pirfenidone are first-line; lung transplant is the only definitive cure.
Prognosis
Poor prognosis with a median survival of 3-5 years post-diagnosis.
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Epidemiology & Etiology
Predominantly affects older males (50-70 years). Strong association with cigarette smoking and chronic micro-aspiration. Genetic predisposition is noted in familial cases, but the etiology remains idiopathic.
Pertinent Anatomy
Fibrosis begins in the subpleural and basal regions of the lungs. Progressive scarring leads to the formation of honeycombing cysts, primarily affecting the lower lobes.
Pathophysiology
Repetitive alveolar epithelial injury triggers an aberrant wound-healing response. This leads to excessive fibroblast proliferation and collagen deposition. The resulting stiff, non-compliant lungs cause restrictive physiology and impaired gas exchange.
Clinical Manifestations
Patients present with insidious, progressive dyspnea and a non-productive cough. Physical exam reveals Velcro-like bibasilar inspiratory crackles and digital clubbing. Acute exacerbations can lead to rapid respiratory failure.
Diagnosis
High-resolution CT (HRCT) is the gold standard, demonstrating usual interstitial pneumonia (UIP) pattern with subpleural reticular opacities and honeycombing. Pulmonary function tests show a restrictive pattern with decreased DLCO.
Treatment
Nintedanib and Pirfenidone are the first-line agents to slow disease progression. Avoid corticosteroids as they provide no benefit and increase mortality. Supplemental oxygen is indicated for hypoxemia; lung transplant is the only definitive treatment.
Prognosis
The disease is progressive and irreversible with a median survival of 3-5 years. Patients are at high risk for pulmonary hypertension and lung cancer.
Differential Diagnosis
Asbestosis: history of shipyard/construction work
Sarcoidosis: hilar adenopathy and non-caseating granulomas
Hypersensitivity pneumonitis: exposure to organic antigens
Connective tissue disease-ILD: presence of systemic symptoms like arthritis
Silicosis: eggshell calcification of lymph nodes