Desquamative interstitial pneumonia (DIP) is an interstitial pneumonia closely related to, and thought to represent the end stage of respiratory bronchiolitis interstitial lung disease (RB-ILD) 1. It is associated with heavy smoking.
Demographics and clinical presentation
There is a recognised male predilection (2:1). The vast majority of patients are heavy smokers (90%) with an average smoking history of 18 pack-years. However, other predisposing factors include:
- systemic disorders, e.g rheumatoid arthritis, scleroderma 7
- infection, e.g. HIV 4
- occupational or environmental exposure, e.g. asbestos 6-7
Presentation tends to be in middle age (30 - 60 years of age) with progressive shortness of breath and chronic cough 4.
Its name is misleading as no desquamation of alveolar epithelium is present, but rather the cells that fill the alveoli are pigment laden macrophages. This is more pronounced than in RB-ILD.
Plain film (CXR)
- non specific
- may show bilateral interstitial infiltrates 8
DIP is characterized by diffuse ground-glass opacities, which correlate histologically with the spatially homogeneous intraalveolar accumulation of macrophages and thickening of alveolar septa:
- bilateral and symmetric : 86% 7
- basal and peripheral : 60%
- patchy : 20%
- diffuse : 20% 4
Other frequent CT findings include spatially limited, irregular linear opacities and small cystic spaces, which are indicative of fibrotic change (50% of patients 7).
Other changes related to background smoking-related lung disease are often seen, e.g. bronchial wall thickening and centrilobular emphysema.
Despite differences in the CT appearance of RB-ILD and DIP, imaging findings may overlap and may be indistinguishable from each other. To improve diagnostic accuracy, lung biopsy is required in all cases of suspected RB-ILD or DIP.
Treatment and prognosis
With smoking cessation and corticosteroid therapy, the prognosis is good. Nevertheless, progressive disease with eventual death can occur, notably in patients with continued cigarette smoking.
See > differential for ground glass opacities
- 1. Attili AK, Kazerooni EA, Gross BH et-al. Smoking-related interstitial lung disease: radiologic-clinical-pathologic correlation. Radiographics. 28 (5): 1383-96. doi:10.1148/rg.285075223 - Pubmed citation
- 2. Miller WT, Shah RM. Isolated diffuse ground-glass opacity in thoracic CT: causes and clinical presentations. AJR Am J Roentgenol. 2005;184 (2): 613-22. AJR Am J Roentgenol (full text) - Pubmed citation
- 3. Heyneman LE, Ward S, Lynch DA et-al. Respiratory bronchiolitis, respiratory bronchiolitis-associated interstitial lung disease, and desquamative interstitial pneumonia: different entities or part of the spectrum of the same disease process? AJR Am J Roentgenol. 1999;173 (6): 1617-22. AJR Am J Roentgenol (abstract) - Pubmed citation
- 4. Naidich DP, Srichai MB, Krinsky GA. Computed tomography and magnetic resonance of the thorax. Lippincott Williams & Wilkins. (2007) ISBN:0781757657. Read it at Google Books - Find it at Amazon
- 5. Katzenstein AL, Myers JL. Idiopathic pulmonary fibrosis: clinical relevance of pathologic classification. Am. J. Respir. Crit. Care Med. 1998;157 (4 Pt 1): 1301-15. Am. J. Respir. Crit. Care Med. (full text) - Pubmed citation
- 6. Freed JA, Miller A, Gordon RE et-al. Desquamative interstitial pneumonia associated with chrysotile asbestos fibres. Br J Ind Med. 1991;48 (5): 332-7. Free text at pubmed - Pubmed citation
- 7. Hartman TE, Primack SL, Swensen SJ et-al. Desquamative interstitial pneumonia: thin-section CT findings in 22 patients. Radiology. 1993;187 (3): 787-90. Radiology (abstract) - Pubmed citation
- 8. Ryu JH, Myers JL, Capizzi SA et-al. Desquamative interstitial pneumonia and respiratory bronchiolitis-associated interstitial lung disease. Chest. 2005;127 (1): 178-84. doi:10.1378/chest.127.1.178 - Pubmed citation
Synonyms & Alternative Spellings
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