Usual interstitial pneumonia

Usual interstitial pneumonia, commonly abbreviated UIP, is the name of a histopathological pattern seen in diffuse lung diseases. Diffuse lung diseases are also referred to as interstitial lung diseases.

UIP is a type of idiopathic interstitial pneumonia. Sometimes, confusingly, it is used as a synoym for idiopathic pulmonary fibrosis.

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Differential diagnosis

UIP is seen in:^[1]

• idiopathic pulmonary fibrosis,
• asbestosis,
• chronic hypersensitivity pneumonitis,
• collagen vascular disease and
• chronic drug toxicity.^[2]

Histologic appearance

UIP is characterized by:

• interstitial inflammation,
• fibroblast foci,
• (microscopic) honeycombing and
• patchy lesional distribution (heterogeneous areas of abnormal and normal lung).

History and application of term

UIP, as a term, first appeared in the pathology literature. It was coined by Averill Abraham Liebow.^[3]

It is sometimes, confusingly, used to refer to idiopathic pulmonary fibrosis, one of its many clinical correlates.

Pneumonia misnomer?

The definition of "pneumonia" is often described as a '... lung inflammation caused by a virus, bacteria or irritant.'^[4]

Etymologically, the usage of "pneumonia" in UIP is correct; the word "pneumonia" is derived from "pneumon" (lung) and the suffix "-ia" (condition).^[5]

See also

• Pneumoconiosis
• Silicosis
• Asbestosis

References