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Introduction High resolution CT (HRCT) guides clinical diagnosis in systemic autoimmune rheumatic disease associated interstitial lung disease (SARD-ILD). Histologic confirmation by lung biopsy is not commonly done or recommended. We evaluated the agreement between HRCT patterns and explant pathology in SARD-ILD patients undergoing lung transplantation.Material and Methods We retrospectively analyzed idiopathic inflammatory myopathy (IIM), systemic sclerosis (SSc),and rheumatoid arthritis (RA)-ILD patients who underwent double lung transplant at two Canadian centers. HRCT-histology agreement was assessed using weighted κ statistics: complete (identical diagnoses, κ =1), partial (e.g., non-specific interstitial pneumonia (NSIP) vs NSIP/usual interstitial pneumonia (UIP), κ=0.5), or no agreement ( κ=0). Results were visualized via Alluvial step-by-step diagrams.Results Among 82 patients (22 IIM, 32 SSc, 28 RA) who underwent lung transplant, RA patients were older, more often smokers, and less frequently female than IIM/SSc. IIM patients most commonly required emergency transplantation (50% vs. 19% for SSc and 36% for RA). Among the 22 IIM patients, the subtypes included: anti-MDA5-positive dermatomyositis (DM) (n=10), antisynthetase syndrome (n=7), overlap myositis (n=3), and seronegative DM (n=2). Rapidly progressive ILD was the transplant indication in 50% of IIM cases. For the 32 SSc patients, ILD was the primary transplant indication. Concomitant pulmonary hypertension was present in 28 patients (88%). Initial HRCT showed NSIP predominance in IIM (59%) and SSc (81%), while UIP dominated in RA (57%). An organizing pneumonia (OP) pattern was observed in 23% of IIM cases but was rare in RA (4%) and absent in SSc. UIP patterns were identified in 9% of both IIM and SSc patients on HRCT. Immediately prior to transplant, a notable proportion of IIM patients (27%) exhibited an evolution to a diffuse alveolar damage (DAD) pattern on HRCT. In contrast, SSc and RA patients largely maintained HRCT patterns consistent with their initial diagnosis. Explant pathology revealed NSIP as the primary pattern in SSc (62%) and UIP in RA (50%). IIM explants exhibited diverse histopathology without dominance. Anti-MDA5+ DM patients universally developed rapidly progressive ILD, progressing to DAD or end-stage fibrosis despite initial NSIP on HRCT. Using weighted κ analysis, we observed moderate HRCT-histology concordance in RA ( κ=0.46, p=0.002), fair but non-significant agreement in SSc ( κ=0.31, p=0.06), and no meaningful correlation in IIM ( κ=0.07, p=0.6).Conclusions SSc-ILD and RA-ILD demonstrated fair-to-moderate HRCT-histology correlation, whereas IIM-ILD shows marked histoplogic heterogeneity independent of imaging patterns. Anti-MDA5+ disease consistently exhibited aggressive progression, underscoring the limitations of HRCT in predicting IIM-ILD pathology.