Morphological CT phenotypes in pulmonary sarcoidosis at diagnosis: splitting and lumping based on predictors of clinical progression

Background Sarcoidosis may represent a broad umbrella term for various diseases that induces non-necrotizing granulomas in affected organs. A recent multinational consensus proposed distinct computed tomography phenotypes for pulmonary sarcoidosis; however, clinical implications remain unclear. Question What is the prevalence of individual phenotypes in a tertiary referral cohort, and are these phenotypes associated with airway involvement and disease progression? Materials and Methods This retrospective study included 232 biopsy-proven pulmonary sarcoidosis patients treated between 2010 and 2020. Baseline CT scans were grouped into (1) non-fibrotic/fibrotic/unclear for fibrosis and (2) normal/nodular/non-nodular. Airway involvement were analysed. Disease progression was assessed over 36 months using predefined clinical, functional and therapeutic criteria. Results Most patients had non-fibrotic phenotypes (91.0%, n=211), while fibrotic (5.6%, n=13) and unclear (3.4%, n=8) patterns were less frequent. Inter-reader agreement was moderate for individual phenotypes (κ=0.55) and good for fibrotic versus non-fibrotic classification (κ=0.79). At 36 months, 69% of patients had progressed; all fibrotic cases progressed, compared with 67% of non-fibrotic. Nodular phenotypes progressed similar to normal CT (64% versus 68%) and lower than non-nodular disease (88%). Fibrotic disease was associated with an increased risk of disease progression after adjustment for age, sex, BMI, and baseline lung function (HR 2.31; 95% CI 1.21–4.38; p=0.038). Answer CT-based seems feasible but my require refinement. Fibrotic patterns predict progression, while “nodular” carries a risk similar to normal CT. Further radiological splitting may not reflect distinct disease behavior.