Multidisciplinary Approach to the Diagnosis of Idiopathic Interstitial Pneumonias: Focus on the Pathologist's Key Role

Idiopathic Interstitial Pneumonias (IIPs) are a heterogeneous group of the broader category of Interstitial Lung Diseases (ILDs), pathologically characterized by the distortion of lung parenchyma by interstitial inflammation and/or fibrosis. The American Thoracic Society (ATS)/European Respiratory Society (ERS) international multidisciplinary consensus classification of the IIPs was published in 2002 and then updated in 2013, with the authors emphasizing the need for a multidisciplinary approach to the diagnosis of IIPs. The histological evaluation of IIPs is challenging, and different types of IIPs are classically associated with specific histopathological patterns. However, morphological overlaps can be observed, and the same histopathological features can be seen in totally different clinical settings. Therefore, the pathologist's aim is to recognize the pathologic-morphologic pattern of disease in this clinical setting, and only after multi-disciplinary evaluation, if there is concordance between clinical and radiological findings, a definitive diagnosis of specific IIP can be established, allowing the optimal clinical-therapeutic management of the patient.

Desquamative Interstitial Pneumonia with Progressive Pulmonary Fibrosis

A 70-year-old man who smoked was referred to our hospital because of progressive cough and dyspnea. Radiologic images showed ground-glass attenuation predominantly in the lower lung lobes. A surgical lung biopsy was performed, and a diagnosis of desquamative interstitial pneumonia (DIP) was made. The patient's symptoms improved with smoking cessation and steroid treatment, but the ground-glass attenuation did not completely resolve. At 10 years after the diagnosis, the fibrotic lesions deteriorated and treatment with nintedanib was subsequently initiated. Careful observation is needed in patients with DIP whose lung involvement does not completely improve with initial treatment.

Sequence of Rare Diagnoses in a Young Patient: Altitude Barotrauma Hemopneumothorax and Desquamative Interstitial Pneumonia

We present the case of a 35-year-old patient without pathological history who developed hemopneumothorax due to altitude barotrauma during a commercial airline flight. The computed tomography (CT) of the chest identified the presence of right hydropneumothorax and emphysema "blebs" and bubbles. After the therapeutic insertion of a drain tube, the patient returned to the country by land transport. Three weeks later, he was diagnosed with right-sided pleurisy based on a CT scan with contrast material. A surgical intervention was then performed, and three biopsy samples were taken; the histopathological result highlighted suggestive elements for the diagnosis of desquamative interstitial pneumonia (DIP).

Unusual pneumoconiosis in two patients with heavy print toner, and paper dust exposure

Workers in a print shop are exposed to photocopier toner dust and paper dust over a prolonged period of time. However, there are only rare case reports of toner and paper dust induced lung damage in humans. We reviewed our consultation files for a period of 30 years from 1987 to 2018 to look for cases with a diagnosis of giant cell interstitial pneumonia (GIP), printer toner exposure and paper dust exposure resulting in lung disease. There were two cases which met our inclusion criteria. Slides, clinical histories and imaging were reviewed. Both the patients had worked in print shops, and had no history of exposure to hard metals. Patient 1 presented with shortness of breath and cough over several months, while patient 2 was asymptomatic at presentation. Both the patients underwent surgical lung biopsies. Histopathologic examination from both the cases showed a spectrum of pathology, including features of GIP, desquamative interstitial pneumonia, chronic bronchiolitis with lymphoid hyperplasia, and particulate matter consistent with toner. Energy dispersive spectroscopy was performed on one case, and it revealed no cobalt or tungsten particles. The unusual combination of findings is very suggestive that toner particles with or without paper dust exposure were responsible for the pathologic changes in the lungs of these patients. This possibility should be explored further with additional patients who work in print shops where they are exposed to paper dust and paper toner and have signs or symptoms of diffuse lung disease.

A case report and literature review

Background

Forms of interstitial pneumonia secondary to exposure to an air-contaminant are varied and so far, insufficiently described.

Objectives/Methods

We report here a case of a 57-year-old patient managed in our department for the exploration of MRC grade 2 dyspnoea and interstitial pneumonia. He mentioned multiple occupational and domestic exposures such as hens' excrements, asbestos and metal particles; he also had a previous history of smoking.

Results

High-resolution computed tomography showed ground glass opacities predominating in posterior territories and surrounding cystic lesions or emphysematous destruction. The entire etiological assessment revealed only macrophagic alveolitis with giant multinucleated cells on the bronchoalveolar lavage. A surgical lung biopsy allowed us to refine the diagnosis with evidence of desquamative interstitial pneumonia and pulmonary granulomatosis. Finally, the analysis of the mineral particles in the biopsy revealed abnormally high rates of Zirconium and Aluminium. We were therefore able to conclude to a desquamative interstitial pneumonia associated with pulmonary granulomatosis linked to metal exposure (Aluminium and Zirconium). The clinical, functional and radiological evolution was favorable after a systemic corticosteroid treatment with progressive decay over one year.

Conclusion

This presentation reports the first case to our knowledge of desquamative interstitial pneumonitis related to exposure to Zirconium and the third one in the context of Aluminium exposure. The detailed analysis of the mineral particles present on the surgical lung biopsy allows for the identification of the relevant particle to refine the etiological diagnosis, to guide the therapeutic management and to give access to recognition as an occupational disease. (Sarcoidosis Vasc Diffuse Lung Dis 2020; 37 (1): 79-84).

Increased Pulmonary GM-CSF Causes Alveolar Macrophage Accumulation. Mechanistic Implications for Desquamative Interstitial Pneumonitis

Desquamative interstitial pneumonia (DIP) is a rare, smoking-related, diffuse parenchymal lung disease characterized by marked accumulation of alveolar macrophages (AMs) and emphysema, without extensive fibrosis or neutrophilic inflammation. Because smoking increases expression of pulmonary GM-CSF (granulocyte/macrophage-colony stimulating factor) and GM-CSF stimulates proliferation and activation of AMs, we hypothesized that chronic exposure of mice to increased pulmonary GM-CSF may recapitulate DIP. Wild-type (WT) mice were subjected to inhaled cigarette smoke exposure for 16 months, and AM numbers and pulmonary GM-CSF mRNA levels were measured. After demonstrating that smoke inhalation increased pulmonary GM-CSF in WT mice, transgenic mice overexpressing pulmonary GM-CSF (SPC-GM-CSF+/+) were used to determine the effects of chronic exposure to increased pulmonary GM-CSF (without smoke inhalation) on accumulation and activation of AMs, pulmonary matrix metalloproteinase (MMP) expression and activity, lung histopathology, development of polycythemia, and survival. In WT mice, smoke exposure markedly increased pulmonary GM-CSF and AM accumulation. In unexposed SPC-GM-CSF+/+ mice, AMs were spontaneously activated as shown by phosphorylation of STAT5 (signal inducer and activator of transcription 5) and accumulated progressively with involvement of 84% (interquartile range, 55-90%) of the lung parenchyma by 10 months of age. Histopathologic features also included scattered multinucleated giant cells, alveolar epithelial cell hyperplasia, and mild alveolar wall thickening. SPC-GM-CSF+/+ mice had increased pulmonary MMP-9 and MMP-12 levels, spontaneously developed emphysema and secondary polycythemia, and had increased mortality compared with WT mice. Results show cigarette smoke increased pulmonary GM-CSF and AM proliferation, and chronically increased pulmonary GM-CSF recapitulated the cardinal features of DIP, including AM accumulation, emphysema, secondary polycythemia, and increased mortality in mice. These observations suggest pulmonary GM-CSF may be involved in the pathogenesis of DIP.

Desquamative interstitial pneumonia: Risk factors, laboratory and bronchoalveolar lavage findings, radiological and histopathological examination, clinical features, treatment and prognosis

Desquamative interstitial pneumonia is a type of smoking-associated major idiopathic interstitial pneumonia, which is characterized by accumulation of alveolar macrophages in alveolar lumens and septa and develops secondary to mainly active or passive exposure to cigarette smoke. Desquamative interstitial pneumonia mostly occurs in male smokers in association with non-specific symptoms responsive to steroid therapy and has a better prognosis than usual interstitial pneumonia. To date, no large-scale clinical studies have been performed on desquamative interstitial pneumonia patients. Factors responsible for the scarcity of data on the clinical course of this condition include the retrospective nature of the available information as well as its rare occurrence. Despite this, a general consensus exists as to the nature of its symptoms, association with smoking, age and gender distribution, findings of respiratory function tests, steroid responsivity and mortality. The objective of the present review article was to report on desquamative interstitial pneumonia and to describe its etiology, risk factors and clinical features, as well as the laboratory, bronchoalveolar lavage, radiological and histopathological findings, and the treatment and prognosis of affected patients.

Desquamative Interstitial Pneumonia Complicated with IgG4-related Lung Disease

As an idiopathic interstitial pneumonia, desquamative interstitial pneumonia (DIP) is an uncommon form of interstitial lung disease and is considered to be a smoking- or dust inhalation-related interstitial pneumonia in the majority of cases. However, the details regarding immunoglobulin G4 (IgG4)-related lung disease remain unclear and controversial. We herein report the first case of DIP complicated with IgG4-related lung disease. Even if a patient has a smoking history, we emphasize the importance of exploring the association between DIP and IgG4-related lung disease to clarify the pathogenesis of these two disorders.

Pulmonary fibrosis and exposure to steel welding fume

BACKGROUND

Arc welders who have been exposed to high concentrations of steel welding fume for prolonged periods of time may develop pulmonary fibrosis but the nature of the fibrotic changes has been debated over the last 80 years without any clear international consensus.

AIMS

To characterize the nature of the pulmonary fibrosis that develops in response to steel welding fume exposure and to provide a working hypothesis that would explain the findings of the existing research, to provide a platform for future research and to inform future occupational and clinical management of welders with pulmonary effects from welding fume.

METHODS

Review of the world literature on pulmonary fibrosis and welding of steel in all languages using PubMed, with further secondary search of references in the articles found in the primary search. Google and Reference Manager were used as further confirmatory search tools.

RESULTS

Only case series and case reports were found but these provided consistent evidence that the consequence of exposure to steel welding fume at high levels for a prolonged period of time is a type of pulmonary fibrosis similar to, and possibly the same as, respiratory bronchiolitis which eventually develops into desquamative interstitial pneumonia with ongoing exposure.

CONCLUSIONS

Steel welding fume may cause an occupational respiratory bronchiolitis which may develop into de squamative interstitial pneumonia with ongoing exposure. This concept may explain the difficulties in interpreting the wider literature on welding fume and lung function at lower exposures and may also explain the increased risk of lung cancer in welders.

The role of the adenosinergic system in lung fibrosis

Adenosine (ADO) is a retaliatory metabolite that is expressed in conditions of injury or stress. During these conditions ATP is released at the extracellular level and is metabolized to adenosine. For this reason, adenosine is defined as a "danger signal" for cells and organs, in addition to its important role as homeostatic regulator. Its physiological functions are mediated through interaction with four specific transmembrane receptors called ADORA1, ADORA2A, ADORA2B and ADORA3. In the lungs of mice and humans all four adenosine receptors are expressed with different roles, having pro- and anti-inflammatory roles, determining bronchoconstriction and regulating lung inflammation and airway remodeling. Adenosine receptors can also promote differentiation of lung fibroblasts into myofibroblasts, typical of the fibrotic event. This last function suggests a potential involvement of adenosine in the fibrotic lung disease processes, which are characterized by different degrees of inflammation and fibrosis. Idiopathic pulmonary fibrosis (IPF) is the pathology with the highest degree of fibrosis and is of unknown etiology and burdened by lack of effective treatments in humans.