Interstitial Lung Disease Diagnosis

Interstitial Lung Diseases (ILD)

• ILD is a group of disorders characterized by inflammation and scarring in the lungs
• Symptoms: loss, fatigue, anorexia, and physical findings of inspiratory crackles and clubbing

Diagnosis

• Diagnosis is based on H&P, Labs, PFT, CXR, HRCT-Chest, BAL, and Biopsy
• Labs: R/O secondary causes of ILD like CT-Diseases
• PFT: restrictive, decreased DLCO
• ABG: hypoxia, normal/low PaCo2
• CXR: ILD, changes more prominent in lower lobes and periphery (subpleural)
• HRCT-Chest: ground glass then honeycombing changes (worse prognosis)
• BAL: increased Neutrophils (NL=1%)
• Biopsy: open lung, confirms the diagnosis
• Histopathology:
  • Usual interstitial pneumonia (UIP): a histopathological term for IPF
  • Desquamative interstitial pneumonia (DIP): more inflammation and better response to steroid
  • Nonspecific interstitial pneumonia (NSIP): more diffuse and without heterogeneity, reversible and better prognosis

Treatment

• Indication: deteriorating or significant symptoms, inflammatory changes (ground-glass opacities) on HRCT
• Treatment options:
  • Steroids and oxygenation
  • Immunosuppressive or cytotoxic agents: azathioprine, cyclophosphamide
  • Antifibrotic agents: colchicine, D-Penicillamine, γ-interferon
  • Lung transplantation (definitive)

Prognosis

• Poor prognosis
• Causes of death: Cor pulmonale, Respiratory failure (3-8 years after onset of Sx.), Malignancy (Adenocarcinoma) is more common

Eosinophilic Granuloma (Histiocytosis X, Langerhans' cell histiocytosis)

• Smokers, M>F
• Presentation: lytic bone lesion, DI (pituitary), Pneumothorax (up to 50%)
• HRCT chest: diffuse centrilobular nodules and cysts formation
• Treatment: stop smoking + steroids

Lymphangioleiomatosis

• Exclusively affects premenopausal women
• Immature SM proliferation in lymphatic, vascular, and alveolar wall
• HRCT-Chest: diffuse thin-walled cystic lesion
• Presentation: recurrent pneumothorax, hemoptysis, chylothorax
• Treatment: No Estrogen, advice against pregnancy, Anti-Estrogen (progesterone), oophorectomy

Desquamative Interstitial Pneumonia

• Smoking-related interstitial disease
• Histopathology: interstitial inflammation and macrophages in alveolar spaces
• HRCT: bilateral ground-glass opacities located in the basal parts of the lung (seen in 92% of patients)
• Responds to steroids

Asbestosis

• Diffuse interstitial fibrosis of the lung caused by inhalation of asbestos fibers
• Predilection for lower lobes
• Increased risk of bronchogenic carcinoma and malignant mesothelioma

Sarcoidosis

• Unknown etiology
• Symptoms:
  • Asymptomatic (CXR)
  • Acute: fever, LÖfgren’s syndrome (triad of skin lesion, polyarthritis, and bilateral hilar lymphadenopathy)
  • Chronic: pulmonary, extrapulmonary
• Presentation:
  • Pulmonary: nonproductive cough, progressive SOB
  • Extrapulmonary:
    • ENT: hoarseness, xerostomia, hearing loss
    • Eye: anterior uveitis (75%), enlarged lacrimal gland (characteristic)
    • Heart: blocks, arrhythmias, CMP
    • Skin: EN, Lupus Pernio
    • Nervous System: Bell’s palsy, meningeal, peripheral neuropathy
• Diagnosis:
  • H&P
  • Labs: ACE (not specific)
  • PFT: usually restrictive changes, decreased DLCO
  • CXR:
    • Stage I: B/L Hilar LN
    • Stage II: B/L Hilar LN + ILD
    • Stage III: ILD (No LN)
    • Stage IV: fibrotic changes (honeycombing), shrinkage the lung
  • Gallium scan
  • Bronchoalveolar lavage: increase T-lymphocyte (CD4+)
  • Biopsy (confirm the diagnosis): transbronchial (more peripheral), mediastinoscopy (for central areas like LN)
• Prognosis:
  • Good prognosis
  • Most are self-limiting
  • Benign course with remission (85%) within 2 years