Desquamative interstitial pneumonia following chronic nitrofurantoin therapy

Desquamative interstitial pneumonia: a systematic review of its features and outcomes

Background

Desquamative Interstitial Pneumonia (DIP) is a rare form of idiopathic interstitial pneumonia (IIP). Data on clinical features, aetiology, prognosis and effect of treatment strategies are limited. We aimed to collect all published cases to better characterise DIP.

Methods

A systematic literature search was performed for all original cases of adult patients with histopathologically-confirmed DIP. Individual patient data were extracted and summarised.

Results

We included 68 individual cases and 13 case series reporting on 294 cases. Most common presenting symptoms were dyspnoea and cough. Pulmonary function showed a restrictive pattern (71%) with decreased diffusion capacity. We found a high incidence (81%) of ever smoking in patients with DIP and 22% of patients had other (occupational) exposures. Characteristic features on high-resolution computed tomography (HRCT) scan were bilateral ground-glass opacities with lower lobe predominance (92%). Treatment and duration of treatment widely varied. Initial response to treatment was generally good, but definitely not uniformly so. A significant proportion of patients died (25% of individual cases) or experienced a relapse (18% of individual cases).

Conclusion

DIP remains an uncommon disease, frequently but not always related to smoking or other exposures. Furthermore, DIP behaves as a progressive disease more often than generally thought, possibly associated with different underlying aetiology.

This systematic review is the most comprehensive collection of published cases of DIP to date and yields novel information about aetiology, clinical characteristics, radiology and pathology features, treatment and outcomes.http://bit.ly/394YRPv

Acute Lung Injury

A wide variety of insults can produce acute lung damage, inclusive of those that injure the lungs directly. The clinical syndrome of acute onset respiratory distress, dyspnea, and bilateral infiltrates is referred to as acute respiratory distress syndrome. The histologic counterpart of acute respiratory distress syndrome is diffuse alveolar damage, classically characterized by hyaline membranes. Other histologic features of acute lung injury include intraalveolar fibrin, organization, interstitial edema, and reactive pneumocytes. Diffuse alveolar damage and other histologic features of acute lung injury are nonspecific as to etiology, and once identified require the pathologist to search the biopsy for further features that may help identify a specific etiology. This chapter reviews the temporal sequence of acute lung injury and explores the large variety of specific etiologic causes with emphasis on helpful histologic features to identify.

Overlaps and uncertainties of smoking-related idiopathic interstitial pneumonias

Smoking-related interstitial lung disease (ILD) consists of a heterogeneous group of disorders that are considered a distinct entity. The 2013 American Thoracic Society and European Respiratory Society recommendations classified respiratory bronchiolitis (RB)/RB-ILD and desquamative interstitial pneumonia (DIP) as smoking-related idiopathic interstitial pneumonias (IIPs). The overlapping histopathological and radiological patterns of smoking-related IIPs must be considered. Overlap patterns of smoking-related IIPs are not easily classified as a single disorder. The initial radiological manifestation and follow-up changes are heterogeneous, even when diagnosed pathologically as RB or DIP. Therefore, a clinical–radiological–pathological consensus is important in the diagnosis of smoking-related IIPs, and long-term evaluation is essential to monitor the morphological changes in these patients. In this article, we reviewed the clinical, radiological, and pathological findings, and also the changes in radiological manifestations of smoking-related IIPs over time.

Smoking-related interstitial lung disease

BACKGROUND

Smoking-related interstitial lung diseases (SR-ILDs) are a heterogeneous group of diseases with major clinical significance. Reliable epidemiological data are not yet available.

METHOD

Review of pertinent literature retrieved by a selective search in PubMed.

RESULTS

The available data on many aspects of SR-ILDs are sparse, but recent studies on the pathophysiology and targeted treatment of these conditions have revealed ways in which clinical outcomes can be improved. Highresolution computerized tomography should be used for differential diagnosis; lung biopsy is often unnecessary. Oncogenic mutations play a role in the pathogenesis of pulmonary Langerhans-cell histiocytosis (PLCH). In the future, cladribine and vemurafenib may be treatment options for PLCH. Desquamative interstitial pneumonia (DIP) may be difficult to distinguish from respiratorybronchiolitis-associated interstitial lung disease (RB-ILD); DIP is treated with steroids and sometimes with immune suppressants. In idiopathic pulmonary fibrosis (IPF), the antifibrotic drugs pirfenidone and nintedanib can delay disease progression. Smoking is also a risk factor for combined pulmonary fibrosis and emphysema (CPFE), rheumatoid-arthritis-associated interstitial lung disease (RA-ILD), pulmonary alveolar proteinosis (PAP), acute eosinophilic pneumonia (AEP), and diffuse alveolar hemorrhage (DAH) in Goodpasture syndrome.

CONCLUSION

In smokers with exertional dyspnea and/or a nonproductive cough, SR-ILDs must be considered in the differential diagnosis. If an SR-ILD is suspected, the patient should be referred to a pulmonary specialist. Early treatment and smoking cessation can improve clinical outcomes, particularly in the acute and chronically progressive types of SR-ILD.

Imaging of macrophage-related lung diseases

Macrophage-related pulmonary diseases are a heterogeneous group of disorders characterized by macrophage accumulation, activation or dysfunction. These conditions include smoking-related interstitial lung diseases, metabolic disorders such as Niemann-Pick or Gaucher disease, and rare primary lung tumors. High-resolution computed tomography abnormalities include pulmonary ground-glass opacification secondary to infiltration by macrophages, centrilobular nodules or interlobular septal thickening reflecting peribronchiolar or septal macrophage accumulation, respectively, emphysema caused by macrophage dysfunction, and honeycombing following macrophage-related lung matrix remodeling.

Pathology of interstitial lung disease

A large and diverse group of pathologic conditions manifests clinically and radiologically as diffuse parenchymal lung disease. Diffuse interstitial lung diseases (ILDs) encompass mainly inflammatory processes that involve the structural elements of this organ. Some ILDs are caused by infections, but most are the result of immunologic, environmental, or toxic mechanisms. Currently, less morbid sampling techniques have increased dramatically the probability that pulmonologists will be faced with establishing a specific and clinically relevant diagnosis using surgical lung biopsy material. Most of the concepts presented in this article have been established using this type of specimen. In the early years of surgical lung biopsy, a small number of diffuse inflammatory conditions came to light that exclusively involved the lungs and did not seem to be caused by infection, toxin, sarcoidosis, pneumoconiosis, or neoplasm. In this article, these idiopathic disorders are discussed in the context of their dominant pathologic findings rather than presented as a separate group of entities.

Nitrofurantoin

For more than 30 years nitrofurantoin has been a widely prescribed and effective agent in the treatment of urinary tract infections. During this time, it has withstood the rigors of constant clinical evaluation and has competed successfully with more recent antibacterial agents. As with many widely used drugs, some serious and potentially hazardous reactions to therapy have been documented. This article reviews and analyzes major reported reactions and interactions from both published and unpublished sources. Incidence rates have been calculated for pulmonary, hepatic, neurological, and hematological responses. Calculated rates of occurrence were very low, and ranged from 0.001 percent of courses of therapy (all types of pulmonary reactions combined) to 0.0007 percent (neurological reactions). Reports on interactions of nitrofurantoin with alcohol, antacids, and oral contraceptives are unfounded and anecdotal. Interactions with nalidixic and oxolinic acids are not clinically significant, and only one case of interaction has been reported with phenytoin. Bioavailability is enhanced by food or propantheline. False positives occur with Benedict's test for urine glucose estimations.