The Diagnosis of IPF
History, physical examination and lung physiology
IPF has an insidious onset. It often presents with persistent dry cough associated with worsening breathlessness and progressive decline in one's exercise capacity. Hemoptysis (coughing up blood) is rare and if it occurs other causes of interstitial lung diseases, such as vasculitis and Iymphangioleiomyomatosis (LAM), should be considered. Most patients with IPF have inspiratory dry crackles ("velcro-type") on auscultation of the chest. Clubbing of the fingers occurs in about half the cases. More advanced cases may present with signs of pulmonary hypertension such as right ventricular heave, loud P2 and tricuspid regurgitation murmur.
Pulmonary function tests (PFT's) typically will demonstrate a restrictive defect, with decreased FVC and TLC, associated with impaired diffusion capacity and often hypoxemia at rest or exercise.
The radiographic patterns of IPF
H. Bobby Nath, MD - Professor of Radiology
Plain chest radiographs are seldom helpful and a high resolution CT scanning of the chest (HRCT) should be obtained whenever ILD is suspected. HRCTs are performed with thin cuts over the lung parenchyma and usually both prone/supine and inspiratory/expiratory views are obtained. No intravenous contrast is necessary.
We now recognize that very close collaboration among clinicians, thoracic radiologists and lung pathologists is absolutely vital so the appropriate correlations are made for the diagnosis of ILD, particularly IPF. Patients older than 50 years, without any significant environmental or occupational exposures and without evidence of any underlying autoimmune disease are very likely to have IPF if the HRCT is felt to have the typical features described below.
A HRCT showing predominantly basilar pleural-based honeycombing along with reticular opacities in the upper lung zones may abrogate the need for a surgical lung biopsy in certain patients suspected of having Idiopathic Pulmonary Fibrosis (IPF). Unfortunately, about 30% to 50% of cases of IPF may not present with this so-called "typical" pattern:
The Pathology of IPF
C. Bruce Alexander, MD - Professor of Pathology
Transbronchial biopsies performed through a bronchoscope will rarely yield the diagnosis in cases of interstitial lung disease, except in cases of cancer with
lymphatic dissemination or granulomatous inflammation. Surgical lung biopsy is the method of choice for the definitive diagnosis of ILDs and Video-Assisted Thoracoscopic procedures (VATS) have become the most favored technique. It is vital that the surgeon obtains samples from at least 3 lobes, staying away from the more obviously fibrotic areas of the lung.
The pattern seen in lung biopsy specimens of patients with IPF is the so-called "Usual Interstitial Pneumonia" or "UIP". Typical findings of UIP will include:
1. Temporally heterogeneous appearance at low magnification, with alternating areas of normal lung, interstitial inflammation, established fibrosis and honeycomb change.
2. Scant, patchy, interstitial inflammation.
3. Patchy deposits of collagen.
4. Presence of fibroblastic foci - areas of "new fibrosis" in the leading edge between normal and fibrotic areas
5. Honeycomb changes.
6. Occasional, focal, intraalveolar macrophage accumulation.
Surgical lung biopsy for the diagnosis of IPF
Robert Cerfolio, M.D.
We are now able to perform lung biopsies using small skin incisions, no larger than two to three inches in length. The surgeon makes three of these small cuts and places a telescope through one, a finger through another (to feel the lung) and a special stapling device through the third. We can remove large or small pieces of lung and are able to visualize the entire lung and heart. The ribs are not spread. Patients have much less pain with this technique called "Video-Assisted Thoracoscopic Surgery (VATS). The operation takes about 20-30 minutes, under general anesthesia, and most patients spend the night in the hospital with discharge the next morning.