Desquamative Interstitial Pneumonia
A 34-year-old female patient was referred to the pulmonary clinic for deteriorating dyspnea and dry cough due to a tobacco use disorder, extreme obesity, and persistent hypoxemic respiratory failure of unknown cause. She stated that she had no history of environmental or occupational exposures, drug usage, or fevers. While getting 3 litres of supplemental oxygen, her oxygen saturation was 93%. Physical examination revealed that the breath sounds were modest yet vesicular. There was no finger clubbing going on. Pulmonary function tests revealed modest limitation and a little decrease in diffusing capacity. The chest computed tomography revealed diffuse ground-glass opacities with peripheral consolidation but no basilar reticulations or honeycombing (Panel A). Based on these findings, the patient was diagnosed with desquamative interstitial pneumonia.
Autoantibody and hypersensitivity pneumonitis testing came back negative, and bronchoalveolar lavage was inconclusive, thus a surgical lung biopsy was conducted. Histopathological examination revealed interstitial fibrosis and significant alveolar filling with pigment-laden macrophages (Panel B, arrows). These findings matched a diagnosis of desquamative interstitial pneumonia, a rare form of idiopathic interstitial pneumonia strongly linked to cigarette smoking. A lung biopsy is required to confirm the diagnosis. Treatment began with a smoking cessation programme and a glucocorticoid lowering dosage. The patient’s symptoms remained constant at the 3-month follow-up while she continued to quit smoking.
Desquamative interstitial pneumonia (DIP) can be distinguished by alveolar macrophage infiltration, interstitial inflammation and fibrosis
Desquamative interstitial pneumonia (DIP) is a condition that is distinguished by significant alveolar macrophage infiltration, followed by interstitial inflammation and fibrosis. DIP is caused by cigarette smoking in about 90% of cases, although it can also occur in nonsmokers, including those with occupational risk factors or a history of using inhalation substances of abuse. Although no genetic problems have been documented in adult-onset DIP, DIP in children is a separate clinical entity with a proven genetic mutation in surfactant protein B and C producing malfunction. It usually indicates a dismal outlook. This article discusses the presentation, evaluation, and management of DIP and emphasises the importance of an interdisciplinary team approach to patient care.
Cigarette smoking has been linked to chronic obstructive pulmonary disease (COPD) and bronchogenic carcinoma, and it has also been linked to the formation and natural history of several types of lung parenchymal illness affecting the interstitium.
Interstitial Lung Disease Caused by Smoking (SR- ILD)
- Langerhans cell histiocytosis of the lungs (PLCH).
- Interstitial lung disease caused by respiratory bronchiolitis (RB-ILD).
- DIP stands for desquamative interstitial pneumonia.
The American Thoracic Society and European Respiratory Society grouped RB-ILD and DIP as smoking-related idiopathic interstitial pneumonia (SR-IIP) in a 2013 statement. Based on their clinical presentation, radiological characteristics, histology, response to treatment, and prognosis, RB-ILD and DIP are distinct entities rather than two points on a continuum. DIP is characterised histologically by an alveolar buildup of macrophages, followed by interstitial inflammation and fibrosis.
Aetiology
Despite being primarily a smoker’s disease, with a reported connection of close to 90%, DIP has also been linked to other exposures and disease conditions such as:
- Marijuana inhalation.
- Copper and beryllium exposure (thus, tool grinders, arc polishers, aluminium arc welders, machinists, tyre manufacturing workers, among others).
- Exposure to fire extinguisher powder and diesel fumes at work.
- Textile workers who use nylon filaments.
- Medications such as sirolimus, nitrofurantoin, tocainide, and sulfasalazine are used.
- Scleroderma and rheumatoid arthritis are examples of autoimmune disorders.
- Recurrent DIP episodes following lung transplant.
It has been linked to infectious aetiologies such as Aspergillus, Hepatitis C, and Cytomegalovirus, as well as metabolic illnesses such as Gaucher disease. Although no genetic problems have been documented in adult-onset DIP, DIP in children is a separate clinical entity with a proven genetic mutation in surfactant protein B and C producing malfunction. It usually indicates a dismal outlook.
Source: NEJM
