diffuse parenchymal lung disease

Diffuse parenchymal lung disease, or DPLD, is an umbrella term for disorders that affect the working tissue of the lung widely rather than in one spot. The word diffuse signals that the abnormality is spread broadly through both lungs, and parenchyma refers to the gas-exchanging tissue itself, the alveoli and their supporting framework.

DPLD is essentially another name for interstitial lung disease, and the two are often used interchangeably. Some specialists prefer DPLD because not all of these conditions are confined strictly to the interstitium; some also involve the air spaces or small airways, making parenchymal a slightly more accurate description.

Classifications group DPLDs by cause or pattern: those with a known cause such as drugs, dusts, or connective-tissue disease; the idiopathic interstitial pneumonias, including IPF; granulomatous diseases such as sarcoidosis and hypersensitivity pneumonitis; and a set of rarer, distinct entities. Sorting a patient into the right box guides both treatment and prognosis.

Because these diseases share symptoms of breathlessness and cough and a restrictive picture on testing, the practical work is in telling them apart. This relies on a structured approach combining history, autoimmune blood tests, high-resolution CT, and, when needed, lavage or biopsy, ideally reviewed by a multidisciplinary team.