High-resolution computed tomographic characteristics in acute farmer's lung and in its follow-up

Abstract

High resolution computed tomography (HRCT) scans are increasingly used in hypersensitivity pneumonitis (HP). This study looked at HRCT findings at different phases of farmer's lung (FL), a common form of HP.A cross sectional analysis of 95 HRCT scans of FL cases (20 acute, 75 with a history of FL, 48 still in contact (Ex +) (dairy farm), and 27 who had ceased contact (Ex-)) was made. All scans were read independently by two, and if needed by three, radiologists blinded to the category. The lungs were divided into six regions (fives lobes + lingula), and read for attenuation/mosaic, ground-glass, micronodules, fibrosis, and emphysema. A score of 0±3 was given for each region and each variable: 0 = absence, 1 =<25% of the surface, 2 = 25±50%, 3 =>50%. Mediastinal lymphadenopathy was also noted.Ground glass, predominating in the lower lobes, was the most frequent feature in the acute and Ex+ cases. Other abnormalities had no preferential distribution. Ex+ had more ground-glass than the Ex-(p=0.0025). Emphysema was more frequently seen than interstitial fibrosis (p=0.004). Mediastinal lymphadenopathy was present in 26 cases (9 acute, 10 Ex+ and 7 Ex-).In conclusion, in farmer's lung: 1) ground-glass predominates in the lower lobes while the other abnormalities have no anatomic predilection; 2) contact avoidance allows a better resolution of computed tomography abnormalities than continued exposure; 3) emphysema is a more frequent finding than interstitial fibrosis; and 4) the presence of mediastinal lymphadenopathy has no negative diagnostic value. Eur Respir J 2000; 16: 56±60.

Small airways diseases, excluding asthma and COPD: an overview

“…They may also reflect ventilation abnormalities related to bronchiolitis with mosaic attenuation on inspiration and air trapping on expiration. Emphysema and fibrosis mimicking usual interstitial pneumonia may be found in chronic disease [220,221].…”

“…Following acute or subacute hypersensitivity pneumonitis, 30-65% of patients remain symptomatic and ,30% develop chronic respiratory failure. Long-term longitudinal cohorts indicate that emphysema with airflow limitation often occurs during follow-up [221,230,231], especially in farmer's lung and in hypersensitivity pneumonitis related to intermittent allergen exposure. Chronic exposure to low concentrations of antigen (e.g.…”

Classification of Hypersensitivity Pneumonitis

“…Considerable confusion surrounds this classification, which is strictly based on patients’ clinical presentation rather than pathophysiological processes. This classification was suggested well before the use of computed tomography to describe HP [3,4,5,6]. HP can have a distinctive histologic appearance when bronchiolocentric cellular interstitial pneumonia, noncaseating granulomas and organizing pneumonia are seen [7, 8].…”

Combinación de fibrosis pulmonar y enfisema: una entidad poco reconocida

“…Otras asociaciones descritas incluyen enfermedades autoinmunes, neumonitis de hipersensibilidad (1,10,11), exposición a minerales (asbestosis, carbón, talcosis) (1, 5, 12-14) y alteraciones congénitas de las proteínas del surfactante (15). La presencia de combinación de fibrosis pulmonar y enfisema en pacientes con enfermedades autoinmunes fue descrita por Cottin et al (7) en un grupo de 34 pacientes (18 con artritis reumatoide, 10 con esclerosis sistémica y 6 con poliautoinmunidad), de los cuales 30 eran fumadores, con un promedio de edad de 57 años (+11) y una relación hombre: mujer de 23:11.…”