Clinical diagnosis
Case 69
【Progress】
He did not hope to take steroid hormone. His symptoms was recovering naturally without any treatment.
【Discussion】
Chronic eosinophilic pneumonia (CEP) is initially found in elevation of counts of eosinophils in peripheral blood. Criteria of CEP for clinical diagnosis does not strictly exist but generally is accepted as follows (1-3) ; persistent respiratory symptoms continues more than 2 weeks; alveolar eosinophilia ≥ 40% at bronchoalveolar lavage (BAL) blood eosinophilia ≥ 1000/mm3 ; pulmonary infiltrates with usually a peripheral predominance on chest imaging ; exclusion of any known cause of eosinophilic lung disease. Our patient experienced dyspnea and cough for a couple of weeks. Chest CT showed patchy opacities predominantly in the peripheral area of the lung. However, the count of eosinophilic cells was 445/ mm3. Then, our case did not fulfill all of the CEP criteria.
As the similar feature of CEP, cryptogenic organizing pneumonia (COP or bronchiolar obstructive organizing pneumonia, BOOP) is listed. The diagnostic criteria of COP are not clearly present. For strict diagnosis of COP, surgical biopsy is reported to be necessary. However, it is not prevailed due to the invasive diagnostic tool. Clinical symptoms are like flu such as fever, persistent cough, malaise and weight loss. Radiograph and chest CT show photographic negative of pulmonary edema and is virtually pathognomonic, which is mimic to CEP. But this characteristic image is present in < 25% of patients (4). Clinical diagnosis of COP is usually delayed since COP is found after antibiotics are not effective and other infectious diseases are ruled out.
The common ground of CEP and COP shares similar radiological and pathological findings except eosinophils infiltration. In short, pathological findings of both specimen of CEP and COP reveal the occupied fibrous components in the lumen of peripheral bronchial tracts such as respiratory bronchioli, alveolar duct and alveolar space (5, 6).
COP is reported to predominantly occur from alveolar wall, implying that occupied alveolar space with fibrous components reflect ground glass opacity, consolidation with air bronchogram and thickening of bronchovascular bundle in radiological findings (5, 7). Interestingly, fibrous components found in CEP and COP, are reversible and migrating (6, 7) but not in usual interstitional pneumonia (UIP). It is reported that the reversible nature is probably acquired with the prominent vascularization mediated by growth factors such as vascular endothelial growth factor (VEGF) and basic fibroblastic growth factor (BFGF) produced by activated T cells (4). The new vessel formation plays an important role for absorption (5, 7). Based on the experimental studies, the pathogenesis of organizing pneumonia is initially intra-alveolar interstisial cells migration from alveolar wall after damage to type 1 pneumocytes (4). Viral inoculations of animal models implicate T-cells in the pathogenesis of organizing pneumonia (4). Namely, T-cells might relate to initiation of COP, migration and reversibility of peripheral lesions. Meanwhile, in CEP, granules of eosinophils persistently damage and destroy the basement membrane of alveoli, inducing the migration of fibroblasts and fibrosis of alveolar lumen (6). Treatment of COP and CEP is based on oral corticosteroids. Respiratory symptoms as well as blood eosinophilia regress within a few hours and chest imaging results normalize within a few days (1, 4).
【Summary】
We present a seventy five-year-old male suffering from slight fever, persistent cough, malaise and weight loss for a couple weeks. Chest CT showed patchy high attenuation lesions in the peripheral lung. Laboratory test revealed slight elevation of eosinophils 400/mm3. Although the count of eosinophils did not fulfill the clinical criteria for CEP, the finding of chest CT is pathognomonic for CEP or COP (BOOP). We should keep in mind that alveolar space can be occupied with fluid (serum or exudate) due to viral pneumonia, pulmonary edema, hemorrhage, cellular components due to bacillus & leukocytes, and fibrous components due to orgdnizing pneumonia. Fibrous components of CEP or CP are migrating and reversible different from usual interstitial pneumonia, probably because of the prominent vascularization mediated by growth factors such as vascular endothelial growth factor (VEGF) and basic fibroblastic growth factor (BFGF) produced by activated T cells. Pathologically, COP (BOOP) occurs from the damage of pneumocyte 1 by T cells and CEP does from the damage of basement membrane by eosinophils .
【References】
1.Marchand E, et al. Idiopathic chronic eosinophilic pneumonia. Orphanet J Rare Dis. 2006; 1: 11.Published online 2006 Apr 6. doi: 10.1186/1750-1172-1-11 PMCID: PMC1464381
2.Jederlinic PJ, et al. Chronic eosinophilic pneumonia. A report of 19 cases and a review of the literature. Medicine (Baltimore) 1988;67:154–162. [PubMed]
3.Marchand E, et al. Idiopathic chronic eosinophilic pneumonia. A clinical and follow-up study of 62 cases. The Groupe d'Etudes et de Recherche sur les Maladies "Orphelines" Pulmonaires (GERM"O"P) Medicine (Baltimore) 1998;77:299–312. doi:10.1097/00005792-199809000-00001.[PubMed] [Cross Ref]
4.Sara AIG, et al. Bronchiolitis obliterans organizing pneumonia: Pathogenesis, clinical features, imaging and therapy review. Ann Thorac Med. 2008 Apr-Jun; 3(2): 67–75. doi: PMCID: PMC2700454
5.Lappi-Blanco E, et al. Intraluminal fibromyxoid lesions in bronchiolitis obliterans organizing pneumonia are highly capillarized. Hum Pathol. 1999;30:1192–6. [PubMed]
6.Mochimaru H, et al. Clinicopathological differences between acute and chronic eosinophilic pneumonia. Respirology. 2005 Jan;10(1):76-85.
7.Lappi-Blanco E, et al. Apoptotic activity is increased in the newly formed fibromyxoid connective tissue in bronchiolitis obliterans organizing pneumonia. Lung. 1999;177:367–76. [PubMed]
2017.8.30