Interstitial lung disease in children

Etiologic spectrum of interstitial lung diseases in Chinese children older than 2 years of age

Background

Childhood interstitial lung diseases (ILD) (chILD) refer to a rare heterogeneous group of disorders. Global collaborations have been working on the etiologies and classification scheme of chILD. With the development of medical technologies, some new diseases were identified to be associated with chILD and its etiologic spectrum is expanding. The aim of this study is to describe the etiologic spectrum of chILD in children older than 2 years of age and summarize the approaches to diagnosis of chILD.

Methods

We made a retrospective analysis of children older than 2 years of age with chILD who referred to Beijing Children’s Hospital from 21 provinces all over China from 2013 to 2018. After excluding pulmonary infection, congenital heart disease, bronchopulmonary dysplasia, bronchiolitis obliterans and bronchiectasis, 133 patients were included and categorized by etiology. Clinical manifestations, high-resolution computed tomography, laboratory data, genetic data and pathologic findings were all collected and reviewed.

Results

Systemic disease associated ILD were the most common causes, accounting for 49.6% of the patients, followed by alveolar structure disorder-associated ILD (27%), exposure related ILD (13.5%), and disorders masquerading as ILD (3.8%). In systemic disease associated ILD, in addition to common etiologies such as vasculitis (10.5%) and connective tissue diseases (9.0%), primary immunodeficiency diseases (PID) associated ILD (9.8%), interstitial pneumonia with autoimmune features (6.8%), and metabolic diseases (6.8%) were not rarely found. Some newly reported etiologies such as STING–associated vasculopathy with onset in infancy, COPA syndrome and STAT3 mutation were included in PID associated ILD. Genetic tests contributed to 15% of the diagnoses which mainly distributed in PID associated ILD, metabolic diseases and surfactant dysfunction disorders, and contributed to the final diagnoses more than lung biopsies (13.5%) and biopsies of rashes or other tissues (12%).

Conclusions

This study first demonstrated an etiologic spectrum of chILD in Chinese children older than 2 years of age and summarized the approaches to diagnosis. The etiologic spectrum of chILD is expanding with more genetic etiologies being recognized.

Idiopathic desquamative interstitial pneumonia in a child: a case report

Background

Desquamative interstitial pneumonia is a rare form of interstitial lung disease in children. Respiratory symptoms appear progressively, are often subtle, and diagnosis is often delayed by a mean of 6 months after onset. High resolution chest computed tomography is the most sensitive imaging technique for demonstrating and identifying interstitial pneumonia. The typical histologic pattern of desquamative interstitial pneumonia, with prominent clustered alveolar macrophages, diffuse reactive alveolar epithelial hyperplasia and globular proteinaceous material, is diagnostic. Desquamative interstitial pneumonia in children can be idiopathic, though it is mostly related to an inborn error of surfactant metabolism.

Case presentation

We present the complex clinical course and pathologic findings of a 30-months-old Mauritian and Senegalese girl with idiopathic desquamative interstitial pneumonia and multiple extrapulmonary manifestations. To our knowledge, this is the first case report of desquamative interstitial pneumonia to occur as part of a syndrome with multiple organ involvement.

Conclusion

We believe that desquamative interstitial pneumonia is not always associated with mutations of the surfactant proteins, and can still be idiopathic, especially when occurring as part of a syndrome with multiple organ involvement, as described in other interstitial lung diseases.

An official American Thoracic Society clinical practice guideline: classification, evaluation, and management of childhood interstitial lung disease in infancy

BACKGROUND

There is growing recognition and understanding of the entities that cause interstitial lung disease (ILD) in infants. These entities are distinct from those that cause ILD in older children and adults.

METHODS

A multidisciplinary panel was convened to develop evidence-based guidelines on the classification, diagnosis, and management of ILD in children, focusing on neonates and infants under 2 years of age. Recommendations were formulated using a systematic approach. Outcomes considered important included the accuracy of the diagnostic evaluation, complications of delayed or incorrect diagnosis, psychosocial complications affecting the patient's or family's quality of life, and death.

RESULTS

No controlled clinical trials were identified. Therefore, observational evidence and clinical experience informed judgments. These guidelines: (1) describe the clinical characteristics of neonates and infants (<2 yr of age) with diffuse lung disease (DLD); (2) list the common causes of DLD that should be eliminated during the evaluation of neonates and infants with DLD; (3) recommend methods for further clinical investigation of the remaining infants, who are regarded as having "childhood ILD syndrome"; (4) describe a new pathologic classification scheme of DLD in infants; (5) outline supportive and continuing care; and (6) suggest areas for future research.

CONCLUSIONS

After common causes of DLD are excluded, neonates and infants with childhood ILD syndrome should be evaluated by a knowledgeable subspecialist. The evaluation may include echocardiography, controlled ventilation high-resolution computed tomography, infant pulmonary function testing, bronchoscopy with bronchoalveolar lavage, genetic testing, and/or lung biopsy. Preventive care, family education, and support are essential.

Clinico-pathologic conference: persistent tachypnea in a 5-week-old boy

The patient was a 5-week-old male admitted with tachypnea and increased respiratory: distress. Mother noted increased cough and increased work of breathing. There was no fever, congestion, or nasal discharge. Prior to presenting to the emergency room, he was given a bronchodilator nebulizer treatment at home with no improvement. Two weeks prior to the current admission, he was hospitalized in the pediatric intensive care unit for approximately two weeks for similar complaints. Physical examination on the current admission was significant for minimal nasal flaring and mild subcostal retractions, with intermittent oxygen requirement. Infectious workup was negative.

Pulmonary interstitial glycogenosis in identical twins

We present the clinical, radiological, and pathological findings of open lung biopsies from monozygotic prematurely born male twins with respiratory distress at ages 6 and 8 weeks postnatally. Radiological examination showed a reticular nodular interstitial pattern on chest radiography. High-resolution computed tomography (HRCT) revealed ground-glass opacification and thickened interstitial septae in both infants. Lung biopsies showed a similar histology. There was diffuse interstitial thickening of the alveolar septa by mesenchymal cells, without prominent hyperplasia of type 2 pneumocytes, and without airspace exudates. Sections were periodic acid-Schiff (PAS)-positive within the cytoplasm of interstitial cells, indicating the presence of glycogen. Thus the diagnosis of pulmonary interstitial glycogenosis was made. Both infants were treated with glucocorticoids and had a favorable outcome. We speculate that pulmonary interstitial glycogenosis could be a histopathological form of chronic lung disease (CLD) of infancy.

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.

Immunohistochemical and in situ detection of cytomegalovirus in lung autopsies of children immunocompromised by secondary interstitial pneumonia

Secondary interstitial pneumonia (SIP), a disease affecting patients immunocompromised by primary underlying diseases during their treatment in hospital, is frequently associated with cytomegalovirus (CMV) infection, a potentially treatable condition. However, in many cases, no infectious agent can be determined, and this clinical disease rapidly progresses to death. Theoretically, SIP could be caused by CMV, which may be present in such small amounts or such configuration that routine histopathological analysis or viral culture techniques cannot detect the virus. To test the hypothesis that immunohistochemistry (IH) and in situ detection by hybridization (ISH) provides more accurate results than the mere histological demonstration of CMV inclusions, these methods were applied to 37 autopsied lung sections obtained from children immunocompromised by primary underlying diseases and who died of SIP. As a result, the cases were subdivided into three groups: (1) children with SIP CMV inclusions (Diffuse alveolar damage-DAD-related) (n = 7); (2) children with SIP without classical viral inclusions (CMV-DAD-related) (n = 3); (3) children with SIP exhibiting nuclear cytopathic effect (not CMV-NSIP-related) (n = 27). In the first group, all three techniques yielded clearly positive results, whereas IH and ISH indicated that three of the children of the second group had CMV-related DAD without histological demonstration of CMV inclusions. In the third group, there were no positive CMV signals. These data indicate that DAD-related CMV infection is an important cause of SIP and of death in children immunosuppressed by primary underlying diseases, and that IH and in situ detection were more sensitive than the histological demonstration of CMV inclusions. A direct involvement of CMV in SIP exhibiting DAD is likely, but not in the non-specific interstitial pneumonia (NSIP) pattern. We conclude that all children with primary underlying diseases should be investigated for CMV SIP using sensitive IH and in situ tests in conjunction with histological routine procedures.

Pulmonary interstitial glycogenosis: a new variant of neonatal interstitial lung disease

We present the clinical, radiologic, and pathologic findings in lung biopsies from seven infants with atypical neonatal lung disease. All seven infants presented with tachypnea, hypoxemia, and diffuse interstitial infiltrates with overinflated lungs on chest radiographs in the first month of life. Lung biopsies from all cases showed similar pathology, with expansion of the interstitium by spindle-shaped cells containing periodic acid-Schiff positive diastase labile material consistent with glycogen. Immunohistochemical staining showed these cells to be vimentin positive but negative for leucocyte common antigen, lysozyme, and other macrophage markers. Electron microscopy revealed primitive interstitial mesenchymal cells with few cytoplasmic organelles and abundant monoparticulate glycogen. Minimal or no glycogen was seen in the alveolar lining cells. Five cases were treated with pulse corticosteroids; hydroxychloroquine was added in one case. Six of seven infants have shown a favorable clinical outcome. One infant died from complications of extreme prematurity and bronchopulmonary dysplasia. Three cases that have been followed for at least 6 years have shown clinical resolution and radiographic improvement. We propose the term "pulmonary interstitial glycogenosis" of the neonate for this new entity to be differentiated from other forms of interstitial lung disease. Because abundant glycogen is not normally found in pulmonary interstitial cells, we postulate an abnormality in lung cytodifferentiation involving interstitial mesenchymal cells.

Smoking-related interstitial lung diseases: a concise review

Interstitial lung diseases (also known as diffuse infiltrative lung diseases) are a heterogeneous group of parenchymal lung disorders of known or unknown cause. These disorders are usually associated with dyspnoea, diffuse lung infiltrates, and impaired gas exchange. The majority of interstitial lung diseases are of unknown cause. Known causes of interstitial lung disease include inhalation of organic and inorganic dusts as well as gases or fumes, drugs, radiation, and infections. This review summarizes the clinical, radiological, and histopathological features of four interstitial lung disorders that have been linked to smoking. These disorders include desquamative interstitial pneumonia, respiratory bronchiolitis-associated interstitial lung disease, pulmonary Langerhans' cell histiocytosis, and idiopathic pulmonary fibrosis. Available evidence suggests most cases of desquamative interstitial pneumonia, respiratory bronchiolitis-associated interstitial lung disease, and pulmonary Langerhans' cell histiocytosis are caused by cigarette smoking in susceptible individuals. Smoking cessation should be a main component in the initial therapeutic approach to smokers with these interstitial lung diseases. In addition, smoking appears to be a risk factor for the development of idiopathic pulmonary fibrosis.

Idiopathic pulmonary fibrosis in infants: good prognosis with conservative management

BACKGROUND

Pulmonary interstitial fibrosis in children is a disease of unknown aetiology, usually associated with a poor prognosis.

METHODS

In this case series we describe 11 children presenting over a 10 year period, managed conservatively and associated with a good prognosis.

RESULTS

In six, symptoms were present from birth and 10 had symptoms at or before 3 months. Diagnosis was made using chest computed tomography and percutaneous lung biopsy. All patients were treated with oral prednisolone. In five no steroid response was noted. One patient responded to hydroxychloroquine. Home oxygen was required in five patients. At follow up all patients are alive at a median age of 6 years (range 1 to 12 years). The two recently diagnosed children have significant symptoms, seven have dyspnoea on exercise, and two are symptom free.

CONCLUSION

The good prognosis seen in these patients is different to previous case reports, indicating a greater than 50% mortality.

Interpretation of the paediatric chest X-ray

Interpretation of the paediatric chest X-ray may appear intimidating at first but knowledge of a few basic rules and an understanding of how the radiographic appearance may be influenced by age and technique will help the clinician arrive at the correct diagnosis in many cases. A structured and logical approach to X-ray interpretation is described, drawing attention to the abnormal signs that should be sought. A limited differential diagnosis is given for some of the more frequent radiological abnormalities seen in children.

Diagnostic accuracy of thin-section CT and chest radiography of pediatric interstitial lung disease

OBJECTIVE

We assessed the accuracy of thin-section CT and chest radiography to diagnose pediatric interstitial lung disease.

MATERIALS AND METHODS

We identified 20 infants, boys, and girls (age range, 1 month to 14 years) with histopathologic confirmation of interstitial lung disease. Six boys and girls without interstitial lung disease were also included. Two observers independently assessed chest radiograph and CT images. The observers stated the most likely diagnosis and a differential diagnosis. We evaluated individual CT features and their distribution.

RESULTS

Observers' diagnoses on CT images were correct (first choice or differential) in 66% of observations versus 45% on chest radiographs (p < 0.025). Correct diagnoses were made on first choice in 61% of CT observations versus 34% on chest radiographs (p < 0.005). Observers were confident (versus uncertain) in 42% of the CT observations versus 18% on chest radiographs; of the confident diagnoses made on CT, 91% were correct. CT interpretations were most accurate in the diagnosis of pulmonary alveolar proteinosis, congenital lymphangiectasia, and idiopathic pulmonary hemosiderosis. All healthy patients examined with CT were correctly identified as such. We noted a distinctive CT pattern in three patients with nonspecific interstitial pneumonitis and one patient with desquamative interstitial pneumonitis; the CT pattern consisted of upper zone predominant honeycombing on a background of ground-glass attenuation.

CONCLUSION

A higher proportion of pediatric interstitial lung diseases can be diagnosed on thin-section CT than on chest radiographs. In our study, confident and correct diagnoses were made more frequently with CT than with chest radiographs.

Bronchoalveolar lavage in children with chronic diffuse parenchymal lung disease

The aim of the present study was to compare cellular and noncellular components of bronchoalveolar lavage fluid (BAL) in a group of children with a diagnosis of chronic diffuse parenchymal lung disease (cDPLD) and a group of children without parenchymal lung disease undergoing BAL for various clinical indications (control group). We evaluated cellular and non-cellular components (total proteins, albumin, hyaluronic acid, and fibronectin) in BAL fluid from 14 children (7 boys and 7 girls; mean age 9.2 years, range 5 months to 18.4 years) fulfilling the clinical and radiological diagnosis of chronic cDPLD, and in 19 controls without evidence of lung disease. The 14 patients were assigned to two study groups: early-stage cDPLD (6 patients; age range 5 months to 5.2 years; duration of illness, 5-7 months) and long-standing cDPLD (8 patients; age range 9.6-18.4 years; duration of illness, 1.2-17.6 years). Ninety-three percent of the patients with cDPLD had at least two BAL constituents outside normal limits, with high numbers of cells, including all types of alveolar cells, but especially lymphocytes and foamy macrophages. These findings indicate a mixed, predominantly lymphocytic alveolitis. Our patients also had a significant increase in two noncellular BAL components, namely fibronectin and hyaluronic acid. BAL samples from children with long-standing cDPLD contained increased numbers of lymphocytes, whereas samples from children with early-stage cDPLD contained increased percentages and numbers of foamy macrophages and increased concentrations of fibronectin, hyaluronic acid, and albumin. In conclusion, we clearly identified an abnormal BAL profile in our group of cDPLD patients. Moreover, BAL findings differentiated younger cDPLD patients in the early stages of their illness from old patients with long-standing disease.

The value of classifying interstitial pneumonitis in childhood according to defined histological patterns

AIMS

Interstitial pneumonitis in children is very rare and most cases have been classified according to their counterparts in adults, although the term 'chronic pneumonitis of infancy' has recently been proposed for a particular pattern of interstitial lung disease in infants. We reviewed our paediatric cases of interstitial pneumonitis, first, to look at the spectrum of histological patterns found in this age group and, second, to determine whether the classification of such cases in childhood is both appropriate and worthwhile.

METHODS AND RESULTS

Twenty-five of 38 open lung biopsies showed an overlapping spectrum of interstitial pneumonitis, including three cases that fulfilled the histological criteria for chronic pneumonitis of infancy. There were 11 cases of reactive pulmonary lymphoid hyperplasia (either lymphoid interstitial pneumonitis or follicular bronchiolitis), five of which were associated with abnormalities of the immune system. Four cases were classified as desquamative interstitial pneumonitis and the remaining seven cases were classified as nonspecific interstitial pneumonitis. There were no cases with the histological features of usual interstitial pneumonitis. Most patients responded to steroids but tended to have a residual deficit in lung function. Mortality appeared to be associated with presentation at a young age.

CONCLUSION

Classification of interstitial pneumonitis according to their adult counterparts is appropriate for this younger age group and can provide valuable information for the clinician. The term 'chronic pneumonitis of infancy' refers to a specific histological pattern, but whether it represents a separate disease or a reflection of pulmonary immaturity remains to be proven.

Evaluation of a diagnostic approach to pediatric interstitial lung disease

OBJECTIVE

To evaluate the value of a systematic approach to the diagnosis of pediatric interstitial lung disease (ILD).

METHODS

In this descriptive, observational, prospective study, we evaluated 51 children presenting with ILD of unknown etiology during a 3-year period. Specific clinical information regarding history, physical examination, diagnostic evaluation, and final diagnosis was recorded on each patient.

RESULTS

A specific diagnosis was established by history and physical examination alone in 1 patient, noninvasive tests alone in 8 others, and invasive tests, including lung biopsy, in another 26. Of the remaining patients, 8 had a suggestive diagnosis, and 8 had no specific diagnosis.

CONCLUSIONS

A systematic approach to the diagnosis of pediatric ILD is useful, and not all patients need lung biopsy for diagnosis.

Diagnostic value of transbronchial, thoracoscopic, and open lung biopsy in immunocompetent children with chronic interstitial lung disease

OBJECTIVES

To evaluate the diagnostic value of transbronchial biopsy (TBB), video-assisted thoracoscopy (VAT), and open lung biopsy (OLB) in immunocompetent children with chronic, diffuse infiltrates; to identify factors that may predict diagnosis in children requiring biopsy; to determine whether age, number of biopsies, or type of procedure are associated with diagnostic yield in children undergoing transthoracic biopsy; and to compare morbidity of VAT with that of OLB.

STUDY DESIGN

As part of a prospective, descriptive study to define the clinical spectrum of pediatric interstitial lung disease, 30 immunocompetent children required TBB, VAT, and/or OLB for diagnosis of diffuse infiltrates. We reviewed and analyzed the following clinical variables: age; preoperative diagnosis; type of procedure; number of lobes undergoing biopsies; durations of surgery, chest tube insertion, and hospitalization; tissue diagnosis; and complications.

RESULTS

Specific diagnoses were made in 50%, 60%, and 53% of patients undergoing TBB, VAT, and OLB, respectively. A variety of rare disorders was found, and tissue diagnosis confirmed the preoperative diagnosis in 25% of all procedures. For patients who underwent transthoracic biopsy, patient age of greater than 24 months was significantly associated with increased diagnostic yield, but the number of lobes biopsied and type of procedure were not. VAT was associated with shorter operating time, chest tube placement, and hospitalization when compared with OLB. The complications of VAT and OLB were comparable.

CONCLUSION

Lung biopsy is an important tool for the diagnosis of interstitial lung disease in immunocompetent children, but the diagnosis of many children, particularly those aged 2 years or younger, remains uncertain.

Factors influencing survival in children with chronic interstitial lung disease

To investigate factors influencing survival in children with chronic interstitial lung disease (ILD), we extracted specific clinical information from a data base of 99 children with ILD who met entry criteria for our study. The effects of a weight below the fifth percentile for the patient's age, crackles, clubbing, family history of ILD, symptom duration, and severity-of-illness score on survival were examined with univariate and multivariate statistical analyses. There were 15 recorded deaths in the group, with a probability that a patient would survive to 24 mo, 48 mo, and 60 mo after onset of symptoms of 83%, 72%, and 64%, respectively. Of the clinical features, only increasing severity-of-illness score was significantly associated with a higher probability of decreased survival. Children with ILD have decreased survival probabilities that can be predicted with a severity-of-illness score.

Interstitial pneumonitis probably induced by cyclophosphamide in nephrosis

A case of interstitial shadows associated with oral cyclophosphamide therapy in a 32-month-old girl with steroid-resistant nephrotic syndrome, who was admitted to the Nishi-Kobe Medical Center with systemic edema, is reported. Due to the lack of response to prednisolone, cyclophosphamide was also administered orally at a dose of 3 mg/kg per day, 4 weeks after the start of steroid therapy. Approximately 3 weeks after the combination treatment she developed a fever, dry cough and cyanosis. Radiographic examination showed diffuse ground-glass shadow in both lungs, presumably indicating that she had interstitial pneumonitis. Her pulmonary signs and symptoms deteriorated despite various antimicrobial treatments. A discontinuation of cyclophosphamide and the administration of high-dose methylprednisolone yielded a dramatic improvement. These findings suggest that the diffuse pulmonary disease in this case was induced by cyclophosphamide. Since interstitial pneumonitis may be fatal and irreversible, attention should be paid to this rare complication even in patients undergoing low-dose oral cyclophosphamide treatment.

Emergency and critical care issues in pediatric rheumatology

The study of critical care issues in pediatric rheumatology is in its infancy, and the available literature is largely case studies and small retrospective series. A child's limited communication skills and the lack of understanding of disease consequences by both parent and child may cause both overuse and underuse of emergency services. To the extent that small case experiences in children with rheumatic diseases do not adequately reflect possible disease presentations or diagnostic and treatment options, pediatric and adult rheumatologists, intensivists, and emergency physicians should readily turn as needed to larger reported experiences in adults with similar conditions.

Familial interstitial lung disease in children: response to chloroquine treatment in one sibling with desquamative interstitial pneumonitis

We describe a male infant with biopsy-confirmed interstitial lung disease (ILD) who responded to chloroquine, after he failed to improve on oral corticosteroids or cyclophosphamide. The infant presented at 8 days of age with respiratory distress and cyanosis. Lung biopsy at 8 weeks of age was consistent with desquamative interstitial pneumonitis (DIP). He was treated with corticosteroids at 2 weeks of age because of a family history of two siblings who died during infancy and who had DIP on postmortem examination. At 8.5 months, our patient was treated with cyclophosphamide because of lack of response to corticosteroids therapy. At 14 months of age, he began treatment with chloroquine in addition to corticosteroids and had a dramatic response within 3 weeks. The patient has been maintained successfully on continuous treatment with chloroquine alone for more than 9 years since this treatment was started.

The diagnostic value of bronchoalveolar lavage in immunocompetent children with chronic diffuse pulmonary infiltrates

We have investigated the diagnostic value of (BAL) in 29 immunocompetent children (ages 1 month to 18 years) with chronic diffuse pulmonary infiltrates on chest radiograph who presented for evaluation over a 3-year period. The median age at the time of the BAL was 20 months with a range of 1-210 months. Positive results (1) diagnostic of a primary disorder; (2) consistent with a diagnosis; or (3) diagnostic of a secondary disorder, were obtained in 20/29 patients (13 with a single positive BAL finding and 7 with more than one finding). BAL was diagnostic of a primary disorder in only 5 patients (17%) with aspiration detected in 3 and infection in 2. The differential diagnosis was narrowed in 15 patients by the presence of lymphocytosis, neutrophilia, or eosinophilia. A secondary disorder was uncovered in 8 patients. Negative results were obtained in 9 additional patients. We conclude that BAL provided useful information in children with chronic diffuse infiltrates, but its ability to determine the primary cause was limited.

Idiopathic pulmonary fibrosis in infants

Idiopathic pulmonary fibrosis is a poorly characterized disease in infants. In the present report, we reviewed our experience with 10 infants during a 10-year period. In 9 patients, onset of symptoms occurred before the age of 2 months and included tachypnea, cough, and inadequate weight gain. However, despite the presence of these symptoms, diagnosis was delayed for 3 months at which time the infants were referred to the pediatric pulmonary department, when the diagnosis was confirmed by open lung biopsy. At the time of admission, bronchoscopy with alveolar lavage was performed in 9 children and showed severe alveolitis with an increase in the neutrophil count. Nine infants were treated with prednisone alone or in combination with chloroquine, colchicine, or cyclophosphamide; all these patients died despite treatment. One infant was treated with pulses of methylprednisolone because of a failure in response to oral prednisone. This girl who displayed similar clinical, radiological, and histological abnormalities as the other children at the time of diagnosis is the only child still alive after 3 years of follow-up. She is now free of respiratory symptoms and has a normal growth curve. The present report raised two important points: (1) a thorough evaluation of characteristic symptoms should lead to an early diagnosis of pulmonary fibrosis in infants; and (2) administration of pulse therapy using corticosteroids has been helpful and needs to be evaluated further.

Interstitial lung disease

Interstitial lung disease in children is a complex group of disorders whose etiology and pathogenesis is not entirely clear. Although the basic pathogenesis has been extrapolated from adult studies, its relevance in the pediatric population can be questioned. Several classifications of this condition have been put forward but Liebow's histologic classification is well accepted. Clinical manifestations are non-specific and can vary from no symptoms and a positive chest X-ray to more characteristic signs and symptoms. The triad of tachypnea, intercostal retractions and dry crackles is characteristic. Chest roentgenograms are a useful diagnostic tool and CT scans help to stage disease severity. Spirometry classically shows a restrictive pattern. Lung biopsy is the gold standard for establishing a diagnosis. Corticosteroids are the cornerstone of treatment in this condition. Thus, in view of the multifactorial nature of this disease, more extensive multi-centre prospective studies are required in order to better understand this rather complex group of disorders.

The role of corticosteroids in respiratory diseases of children

Glucocorticosteroids are potent anti-inflammatory agents and have an important role in a variety of respiratory diseases. Although their exact mode of action is unknown, it is thought that they exert their effects by binding to cytoplasmic glucocorticoid receptors. In certain conditions, such as asthma, the value of steroids cannot be questioned, and inhaled steroids have revolutionized management. In other situations, such as interstitial lung disease, the true role of steroids is still to be defined. In the management of diseases such as tuberculosis, the use of steroids is solely based on anecdotal experience.