Interstitial lung diseases (ILD) in children
comprise a diverse group of rare conditions involving the interstitium
as well as the distal airspaces that result in restrictive lung
physiology and derangements in oxygenation. The expression and outcome
of pediatric ILD differs from adult ILD as the disease occurs during the
growing phase of the lung and extrapolation of information obtained from
adult studies has been debated. Several classifications for ILD have
been proposed but none have been found to be entirely satisfactory
especially in children. Since ILD comprises of heterogenous group of
disorders, it is logical to approach the disease as unknown etiology
(idiopathic), known etiology and ILD unique to infancy.
Authors of the study published in this issue of
Indian Pediatrics [1] have done extensive research and classified
patients with ILD as definite and possible subgroups. Since ILD occurs
frequently in the younger children and causes are different from adults,
future research should concentrate on younger patients. Idiopathic ILD
requires a tissue diagnosis. The lung histological patterns that can be
observed in ILD have been reviewed by the ATS/ERS [2]. Some idiopathic
disorders described in adults like desquamative interstitial pneumonia
(DIP), non-specific interstitial pneumonia (NSIP), lymphocytic
interstitial pneumonia (LIP) are reported in children also. NSIP has
been reported with connective tissue and surfactant disorders and LIP
with immunodeficiency states.
It is our observation that in children with
idiopathic ILD the mean survival duration was about two and half years.
Acute interstitial pneumonia (formerly Hamman-Rich syndrome), rapidly
progresses to fatal respiratory failure was also reported in children
[3]. Interstitial lung disease unique to infancy includes cellular
intersititial pneumonitis of infants, chronic pneumonitis of infancy,
familial DIP, idiopathic pulmonary fibrosis of infancy, infantile
pulmonary hemosiderosis, surfactant dysfunction disorders and persistent
tachypnea of infancy. [4]. The study published in this issue [1] though
discusses both unknown and known causes, contributes significant
information on the latter group. Chronic aspiration, pulmonary
hemosiderosis, pulmonary alveolar proteinosis, Langerhans cell
histiocytosis, hypersensitivity pneumonitis, sarcoidosis, and lymphocyte
infiltrative disorders come under known etiology and majority of them
may be diagnosed without biopsy where bronchoalveolar lavage (BAL) plays
an important role [5].
Except the acute form, children with ILD have
symptoms for years before the diagnosis. Due to rarity of the condition
and lack of awareness, the victims are subjected to repeated chest
skiagrams, antibiotics and anti-tuberculosis therapy. Cough, dyspnea,
failure to thrive, exercise intolerance, retractions, inspiratory (velcro)
crackles and hypoxemia are the features associated with initial
presentation, and when these are not explained by an alternative
diagnosis, ILD should be suspected. The usefulness of BAL and HRCT has
been well emphasized in the study. HRCT should be included in the early
diagnostic workup of ILD which may show geographical hyperlucency,
septal thickening and ground glass opacity and to optimise spatial
resolution thin slice cuts of one mm collimation is recommended [6].
In a resource poor setting, a systematic approach
integrating strong suspicion, a thorough clinical evaluation and HRCT
may be suffice for the diagnosis and biopsy is rarely indicated as the
specimen obtained may not always be a representative sample [7] and this
fact has been highlighted in the present study. In our opinion, lung
biopsy can be included in the workup of "unknown etiology" group as it
may throw more light on this medical enigma particularly in centers
equipped with video assisted thoracoscopy. Although spirometry and
pulse-oximetry do not provide specific information, they do play a role
during follow-up. Authors of present study assigned ILD scores which may
predict the outcome in individual cases.
Oral prednisolone or pulsed intravenous methyl
prednisolone, singly or in combination with hydroxychloroquine, are
commonly used drugs and children with significant disease are better
treated with pulsed methyl prednisolone. The aim of treatment is to
maintain the patient on the minimum dose of steroid compatible with
clinical stability.
Collaborative multicentric studies in pediatric ILD
focusing on molecular mechanisms, pathophysiology and natural history
are the need of the hour which may save the affected children from an
expensive diverse battery of investigations and inappropriate therapy.
The research paper published in this issue will raise awareness about
ILD among pediatricians.
1. Sankar J, Pillai MS, Sankar MJ, Lodha R, Kabra SK.
Clinical profile of interstitial lung disease in children. Indian
Pediatr;2013:50:127-33.
2. American Thoracic Society/European Respiratory
Society International Multidisciplinary Consensus. Classification of the
idiopathic interstitial pneumonias. Am J Respir Crit Care Med.
2002;165:277-304.
3. Vijayasekaran D, Giridhar S, Gowrishankar NC,
Nedunchelian K, Senguttuvan M. Pediatric interstitial lung disease.
Indian Pediatr. 2006;43:899-903.
4. Dishop MK. Paediatric interstitial lung disease:
classification and definitions. Paediatr Respir Rev. 2011;12:230-7.
5. de Blic J, Midulla F, Barbato A, Clement A, Dab I,
Eber E, et al. Bronchoalveolar lavage in children. ERS Task Force
on Bronchoalveolar Lavage in Children. European Respiratory Society. Eur
Respir J. 2000;15:217-31.
6. Clement A. Task force on chronic interstitial lung
disease in immunocompetent children. Eur Respir J. 2004;24:686-97.
7. Fan LL, Kozinetz CA, Deterding RR, Brugman SM.
Evaluation of a diagnostic approach to pediatric interstitial lung
disease. Pediatrics. 1998;101:82-5.
