Lung - nontumor
Other interstitial pneumonitis / fibrosis
Desquamative interstitial pneumonitis (DIP)

Author: Elliot Weisenberg, M.D. (see Authors page)

Revised: 28 February 2017, last major update September 2011

Copyright: (c) 2003-2017,, Inc.

PubMed search: desquamative interstitial pneumonitis [title]

Cite this page: Desquamative interstitial pneumonitis (DIP). website. Accessed February 24th, 2018.
Definition / general
  • Usually adults with insidious onset of shortness of breath, progressing to respiratory insufficiency; also cough, cyanosis and clubbing
  • Cause unknown
  • Mean survival of 12 years, mortality 28%
  • 90% are current or past cigarette smokers; male:female = 2:1
  • Patients who stop smoking + / - steroid therapy have good prognosis
  • Associated with collagen vascular disease, positive ANA (similar to UIP)
  • Xray: bilateral, lower lobe, ground glass infiltrates
  • Steroids (respond better than UIP)
Microscopic (histologic) description
  • Diffuse collections of intraalveolar macrophages containing lipid and PAS+ granules (originally thought to be desquamated pneumocytes)
  • Type II pneumocyte hyperplasia, acute and chronic inflammatory cells
  • May be focal interstitial fibrosis
  • No necrosis, no hyaline membranes and no fibrin
Positive stains
  • PAS after diastase, iron
Electron microscopy description
  • Type II pneumocytes contain lamellar bodies (surfactant)
  • May be phagocytosed by macrophages
Differential diagnosis
  • DIP reaction to Langerhans cell histiocytosis
  • Extrinsic allergic alveolitis
  • Asbestosis
  • Respiratory bronchiolitis