Clinical and Radiological Features of Various Variants of Extrinsic Allergic Alveolitis

Objective. To optimize diagnosis of various variants of morphologically verified extrinsic allergic alveolitis (EAA), by determining the most significant clinical and radiological indicators of its development.

Material and methods.  Examinations were made in 82 patients  with morphologically confirmed EAA, including 10 people with acute EAA, 38 with subacute EAA, 26 with chronic EAA, and 8 with recurrent EAA. Their medical history data were studied; physical examination, clinical blood, pulmonary function (PF), and lung diffusing capacity tests, and high-resolution  computed tomography (HRCT) of the chest were performed. Transbronchial and/or  video-assisted thoracoscopic lung biopsies were used for morphological studies.

Results. Four disease course variants were identified. Disease duration, adherence to a specific antigenic effect, and the clinical, radiological, and morphological patterns of the disease were determined for its each variant.

Conclusions. 1. Acute EAA is characterized by an abrupt onset and rapid (no more than 3 months) development with a preponderance of intoxication syndrome (Cumulative Index (CI), 2.1 ± 0.2 scores); subacute EAA is characterized by a slower (8.5–10 months) development with a predominance of respiratory symptoms (CI, 2.5 ± 0.1 scores), the steady progression of which is observed in chronic EAA (CI, 2.9 ± 0.2 scores). Recurrent EAA  in  previously cured  patients  is  accompanied  by both  syndromes simultaneously  (CI, 2.7 ± 0.3). 2. The characteristic feature of acute EAA on HRCT of the chest is the extent of ground-glass opacity in both lungs (more than 3 segments) and perivascular infiltrates; that of subacute EAA is microfocal dissemination; that of chronic EAA is macrofocal changes in the presence of interlobular septal thickening, as well all the development of cystic changes in the subpleural zones. In recurrent EAA, all the listed symptoms may appear. 3. Enlarged intrathoracic lymph nodes are most common in subacute EAA in 45.9% of cases and less common in acute and chronic EAA in 20 and 23.8% of cases, respectively. In all disease variants, lymph node hypertrophy affects the bifurcation and paratracheal groups and less often the bronchopulmonary and tracheobronchial groups; the sizes vary from 11 to 20 mm with means of 13.0 ± 1.2 mm.

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