Fibrotic Patterns and Diagnostic Correlates in Hypersensitivity Pneumonitis: Clinical, Radiologic, and Hematologic...

Background: Hypersensitivity pneumonitis (HP) is an interstitial lung disease characterized by immune-mediated inflammation and variable degrees of fibrosis. Aims: To evaluate the clinical, radiological, and hematological features of patients diagnosed with HP. Study Design: Retrospective cross-sectional study. Methods: We included 100 patients diagnosed and followed for HP between 2020 and 2024. Demographic characteristics, pulmonary function test results, diffusing capacity, six-minute walk test findings, antigen exposure history, and high-resolution computed tomography (HRCT) patterns were retrospectively analyzed. Results: The mean age was 63 ± 14 years, with equal sex distribution. Sixty-five percent of patients had identifiable antigen exposure, predominantly related to birds or bird products (86.4%). Surgical lung biopsy confirmed the diagnosis in 29% of cases. The most common HRCT findings were reticulation (87%), ground-glass opacities (84.7%), and centrilobular nodules (75%); fibrotic features were present in 48% of patients. Glucocorticoids were the main treatment (77%), and antifibrotic therapy was used in 20% of cases. Neutrophil count showed a modest positive correlation with honeycombing (r = 0.27, p = 0.025). Basophil count demonstrated a mild association with bird-related antigen exposure (r = 0.26, p = 0.035). Conclusions: Peripheral neutrophil and basophil counts showed weak but statistically significant associations with fibrotic HRCT features and exposure patterns. These exploratory findings suggest that routinely available hematologic parameters may provide supportive information alongside radiologic and clinical data. Prospective studies are needed to validate their diagnostic and prognostic relevance in HP.