Eosinophilic interstitial lung disease

Although rare, the eosinophilic lung diseases are being increasingly identified as distinct clinical entities. These disorders are a heterogeneous group of disorders in which there is an increased number of eosinophils in the airways and/or lung parenchyma. These disease entities may be broadly separated into airway disorders (asthma, allergic bronchopulmonary mycosis, eosinophilic bronchitis, and bronchocentric granulomatosis) and parenchymal (interstitial) disorders. This review and update will concentrate on the latter group of entities.

Recent publications in the field have concentrated on expanding the list of causative agents and clinical situations. An especially promising number of articles report advancements in the understanding of the pathogenetic mechanisms behind the development of the clinical syndromes.

Whatever the function of the eosinophil in these disorders, it is important to remember that the disease processes lumped together as the eosinophilic lung diseases are a heterogeneous group of diseases. In an attempt to categorize these disorders, they have been connected, either appropriately or artificially, by their association with the eosinophil. Nevertheless, the eosinophilic connection may serve as a clue to pathogenesis and treatment.