Hypersensitivity pneumonitis: lessons for diagnosis and treatment of a rare entity in children

Hypersensitivity pneumonitis (HP) also called exogenous allergic
alveolitis = extrinsic allergic alveolitis in children is an
uncommon condition and may not be recognized and treated
appropriately. To assess current means of diagnosis and therapy and
compare this to recommendations, we used the Surveillance Unit for
Rare Paediatric Disorders (ESPED) to identify incident cases of HP
in Germany during 2005/6. In addition, cases of HP reported for
reference from all over Germany to our center in the consecutive
year were included. Twenty-three children with confirmed pediatric
HP were identified. All (age 9.4 y (4.4-15.1) presented with
dyspnoea at rest or with exercise, mean FVC was 39% of predicted,
seven of the 23 children already had a chronic disease state at
presentation. IgG against bird was elevated in 20, and against
fungi in 15. Bronchoalveolar lavage was done in 18 subjects (41%
lymphocytes, CD4/CD8 1.99), and lung biopsy in 6. Except 2, all
children were treated with prolonged courses of systemic steroids.
Outcome was not favourable in all cases. Late diagnosis in up to a
quarter of the children with HP and inappropriate steroid treatment
must be overcome to improve management of HP. Inclusion of children
with HP into international, web-based registry studies will help to
study and follow up such rare lung diseases.