Usual interstitial pneumonia is a form
of lung disease characterized by progressive scarring of both lungs. The
scarring involves the supporting framework of the lung. UIP is thus
classified as a form of interstitial lung disease. The term “usual” refers to
the fact that UIP is the most common form of interstitial fibrosis.
“Pneumonia” indicates “lung abnormality”, which includes fibrosis
and inflammation. A term previously used for UIP in the British literature is
cryptogenic fibrosing alveolitis, a term that has fallen out of favor since the
basic underlying pathology is now thought to be fibrosis, not
The cause of the scarring in UIP may be known or unknown. Since the medical term
for conditions of unknown cause is “idiopathic”, the clinical term for UIP
of unknown cause is idiopathic pulmonary fibrosis. Examples of known causes of
UIP include systemic sclerosis/scleroderma, rheumatoid
arthritis, asbestosis, and chronic nitrofurantoin toxicity.
Symptoms The typical symptoms of UIP are
progressive shortness of breath and cough for a period of months. In some
patients, UIP is diagnosed only when a more acute disease supervenes and brings
the patient to medical attention. Diagnosis
UIP may be diagnosed by a radiologist using computed tomography scan of the
chest, or by a pathologist using tissue obtained by a lung biopsy.
Radiologically, the main feature required for a confident diagnosis of
UIP is honeycomb change in the periphery and the lower portions of the lungs. The
histologic hallmarks of UIP, as seen in lung tissue under a microscope by a
pathologist, are interstitial fibrosis in a “patchwork pattern”, honeycomb
change and fibroblast foci. Pathological findings in usual
interstitial pneumonia Differential diagnosis
The differential diagnosis includes other types of lung disease that cause
similar symptoms and show similar abnormalities on chest radiographs. Some
of these diseases cause fibrosis, scarring or honeycomb change. The most
common considerations include: chronic hypersensitivity pneumonitis
non-specific interstitial pneumonia sarcoidosis
pulmonary Langerhans cell histiocytosis asbestosis
Prognosis Regardless of etiology, UIP is
relentlessly progressive, usually leading to respiratory failure and
death. Some patients do well for a prolonged period of time, but then
deteriorate rapidly because of a superimposed acute illness. The outlook
for long-term survival is poor. In most studies, the median survival is 3 to 4
years. Patients with UIP in the setting of rheumatoid arthritis have a slightly
better prognosis than UIP without a known cause.
History UIP, as a term, first appeared in the
pathology literature. It was coined by Averill Abraham Liebow.
See also Pneumoconiosis
Idiopathic pulmonary fibrosis Pulmonary fibrosis
References External links
Coalition for Pulmonary Fibrosis: Pulmonary Fibrosis Patient Services,
Education; Funding Research to Find a Cure for PF – coalitionforpf.org.
PA-IPF – The Pennsylvania Idiopathic Pulmonary Fibrosis State Registry at
University of Pittsburgh