Interstitial Lung

Diseases

Dr. Rahul Magazine

M.D.(Medicine), D.T.C.D.

Department of Pulmonary Medicine

Definition

The interstitial lung diseases (ILDs) represent

a large number of heterogeneous disorders

that involve the parenchyma of the lung -- the

alveoli, the alveolar epithelium, the capillary

endothelium, and the spaces between these

structures, as well as the perivascular and

lymphatic tissues.

Classification 1. DPLD of Known Cause (drugs or

association such as collagen vascular disease)

2. Idiopathic interstitial pneumonias

• Idiopathic Pulmonary Fibrosis (UIP pattern)

• IIP other than IPF (e.g. NSIP,DIP,AIP, RB-ILD, COP, LIP)

3. Granulomatous DPLD (Sarcoidosis)

4. Other forms of DPLD (e.g. LAM, PLCH)

EPIDEMIOLOGY

• Incidence 30 / 100000 per year (USA)

• Incidence higher in men

PATHOGENESIS

ILDs are the result of the superimposed

processes of inflammation and tissue injury and

attempted repair

Two major histopathologic patterns:

GRANULOMATOUS LUNG DISEASE

This process is characterized by an

accumulation of T lymphocytes, macrophages,

and epithelioid cells organized into discrete

structures (granulomas) in the lung

parenchyma. The granulomatous lesions can

progress to fibrosis.

INFLAMMATION AND FIBROSIS

The initial insult is an injury to the epithelial

surface causing inflammation in the air

spaces and alveolar walls. If the disease

becomes chronic, inflammation spreads to

adjacent portions of the interstitium and

vasculature and eventually causes interstitial

fibrosis.

CLINICAL PRESENTATION

HISTORY

Breathlessness (most common): Initially, dyspnea on exertion→ later at rest

Nonproductive cough

Fatigue

Pleuritic chest pain

Hemoptysis-- infrequent

A family history of ILDs should be sought.

D/D BASED ON ONSET: ACUTE ONSET: DAYS TO WEEKS

Acute interstitial pneumonia

Acute pneumonitis from collagen vascular

disease(especially SLE)

Diffuse alveolar hemorrhage

Hypersensitivity pneumonitis

CHRONIC: MONTHS TO YEARS

Idiopathic pulmonary fibrosis

Chronic hypersensitivity pneumonitis

Collagen vascular disease–associated ILD

PHYSICAL EXAMINATION

PULMONARY SIGNS

With advanced disease, patients may have tachypnea and tachycardia, even at rest.

Bilateral, basilar, Velcro-like rales

Signs of pulmonary hypertension

EXTRAPULMONARY SIGNS:

Clubbing (e.g. IPF)

Skin abnormalities, peripheral

lymphadenopathy, hepatosplenomegaly

(SARCOIDOSIS)

Subcutaneous nodules (RHEUMATOID

ARTHRITIS)

Muscle tenderness and proximal weakness

(POLYMYOSITIS)

INVESTIGATIONS

CHEST RADIOGRAPHY

Nodules, linear (reticular) infiltrates, or a

combination of the two (reticulonodular

infiltrates)

Diffuse ground glass pattern– EARLY

Cystic areas (honeycomb pattern)-LATE

HIGH-RESOLUTION CT scan

PULMONARY FUNCTION TESTS

Reduced lung volumes, reduced diffusing

capacity (DLCO ),a normal or supernormal

ratio of FEV1 to FVC, Static lung

compliance is decreased (decreased lung

volume for any given transpulmonary

pressure), and maximal transpulmonary

pressure is increased (a very high

negative pressure must be generated to

open the fibrotic alveoli)

ARTERIAL BLOOD GAS ANALYSIS

BRONCHOSCOPIC STUDIES

Bronchoalveolar lavage

LUNG BIOPSY

Transbronchial biopsy

Open-lung or thoracoscopic biopsy

TREATMENT

Principal aims:

(1) to remove exposure to injurious

agents,

(2) to suppress inflammation to prevent

further destruction of the pulmonary

parenchyma, and

(3) to palliate the manifestations of these

diseases.

CORTICOSTEROIDS: mainstay of therapy

Prednisone, 1 mg/kg for 1 month, followed by 40 mg/day given for 2 months

Gradually tapered (5 mg/week) over several months to a maintenance dose of 15 to 20 mg/day

Corticosteroids are continued until pulmonary function is stable for 1 year

Relapses require returning to high-dose steroids

Cytotoxic agents (Cyclophosphamide)or immunosuppressive agents (Azathioprine) may be used in patients who do not improve on steroid therapy or who cannot tolerate corticosteroids

Thank You