© 2002 American Thoracic Society
Rare Lung DiseasesOrphans No More?Royal Brompton Hospital London, United Kingdom Diffuse lung diseases have been viewed, until the last 5 to 10 years, as the "Cinderella" subspecialty of lung medicine. There are multiple reasons for this, including their relative rarity and problems with precise diagnosis. Diagnostic difficulties have been due in part to imprecision of classification. Since 1999, four major statements on the diagnosis and management of diffuse parenchymal lung disease have been published: on the assessment and treatment of diffuse lung diseases; on idiopathic pulmonary fibrosis; on the diagnosis and management of sarcoidosis; and, more recently, on the classification of idiopathic interstitial pneumonias (1–4). With these statements has come a greater understanding of, and a greater interest in, the diseases that affect the lung parenchyma. This has been reflected in an increase in collaborative studies and, possibly more important for the patient, an increase in the interest of the pharmaceutical industry in sponsoring trials to attempt to improve the outcome of these diseases, which often behave in a malignant fashion. There are a number of other diseases that are even more "orphan" in their appreciation. The term "orphan" denotes diseases that either because of their rarity or paucity of therapeutic options are less well understood by patients and their caregivers. This results in a significant group of patients who feel quite disenfranchised in terms of obtaining information about their disease or of hoping for an effective outcome. In 1993, a French co-operative, the Groupe d'Etudes et de Recherche sur les Maladies "Orphelines" Pulmonaires (GERM"O"P), was founded under the leadership of Jean-François Cordier in Lyon. The goal of this co-operative was to acquire information from sufficiently large cohorts of patients with rare diseases to improve understanding of and research into these diseases. To date, the registry includes 1,483 patients enrolled by 196 French-speaking clinicians. This has resulted in a series of publications and presentations based on large patient numbers that have improved our understanding of diseases such as cryptogenic organizing pneumonia, lymphangioleiomyomatosis, and idiopathic chronic eosinophilic pneumonia (5–7). Importantly, this group has evolved its role by attempting to improve patient knowledge by the production of information packs that aim to inform and demystify these rare diseases. In this issue of AJRCCM (pp. 1235–1239), we see the latest outcome of the GERM"O"P registration and data analysis program in an article by Philit and coworkers (8) in which a group of 22 individuals with idiopathic acute eosinophilic pneumonia is described. Although the condition has been reported previously and the features are reasonably well defined (9, 10), this article provides added value. I highlight three features. First, classification of eosinophilic pneumonia is confusing: this is the largest cohort reported so far and it will provide a sounder basis for further clarification. Second, the authors show that disease duration before presentation can be as long as 30 days, but that the clinical features and outcome do not differ between early and late presenters. Third, and arguably most importantly, the authors point out that this disease can present with respiratory failure that mimicks acute lung injury or acute respiratory distress syndrome, but is reversible and can be diagnosed by a combination of imaging, particularly high-resolution computed tomography, and bronchoalveolar lavage—key clinical information. Increasingly, we are being made aware that the pattern recognition afforded by high-resolution computed tomography, taken together with the cellular patterns of bronchoalveolar lavage, can increase the precision of diagnosis, thereby precluding the need for surgical biopsy. This has now been acknowledged in idiopathic pulmonary fibrosis, in which a coarse peripheral reticular, especially honeycomb, pattern associated with lavage neutrophilia with or without eosinophilia increases the confidence of diagnosis to virtually 100%. In this current article by Philit and coworkers (8), I infer that the same could be true of acute eosinophilic pneumonia. This has immense implications in terms of a patient on the borders of respiratory failure, who might otherwise require mechanical ventilation to allow a surgical biopsy to be performed. This is a retrospective study and the authors recognize the limitations of retrospective analyses such as this, most notably the absence of a complete data set: this is an almost inevitable consequence of the approach they have taken, but this collaborative approach has significantly more value than a cluster of case reports in terms of reliability of the take-home message. This study set out to define and characterize idiopathic acute eosinophilic pneumonia with more precision. For me, however, two other important messages emerge from the study. The first is the added value of collaboration. The GERM"O"P has been singularly successful for almost a decade. The French are to be commended on this initiative and this should be reproduced throughout the rest of Europe and worldwide. In this regard, the United States has a long track record of collaborative studies in lung diseases as diverse as primary pulmonary hypertension, vasculitis, and sarcoidosis. A further effort to combine resources to understand these rarer diseases now has a commendable template. The second message that I take from this article is the possible renaissance of bronchoalveolar lavage. High-resolution computed tomography has shown us how well we can define the macroanatomy of diffuse lung disease and lavage can provide added security of diagnosis: could this provide the platform we need for a rationalization and standardization of an investigative resource that we have undervalued for too long? REFERENCES
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