Interstitial lung diseases (ILDs) represent a heterogeneous group of over 200 chronic lung disorders characterized by varying degrees of inflammation and fibrosis of the lung interstitium, leading to impaired gas exchange and progressive respiratory failure (1). The accurate diagnosis and management of ILDs remain challenging due to overlapping clinical, radiological, and pathological features. A multidisciplinary approach involving pulmonologists, radiologists, and pathologists has increasingly become the gold standard in evaluating ILDs to ensure diagnostic accuracy and improve clinical outcomes (2). High-resolution computed tomography (HRCT) plays a pivotal role in the initial assessment, often revealing characteristic patterns such as usual interstitial pneumonia (UIP) or nonspecific interstitial pneumonia (NSIP), which can guide subsequent diagnostic steps (3). However, radiological findings may be inconclusive or mimic other fibrotic lung diseases, necessitating histopathological confirmation through surgical lung biopsy or cryobiopsy in selected cases (4).

Despite advancements, the concordance between radiological and histological patterns remains suboptimal in some subtypes of ILD, particularly in differentiating UIP from NSIP and chronic hypersensitivity pneumonitis (5). Several studies have addressed the radiological-pathological correlation in ILDs. Walsh et al. (2016) reported that multidisciplinary discussion improved interobserver agreement and diagnostic confidence in fibrotic lung diseases (6). Similarly, studies by Flaherty et al. (2022) emphasized that integrating clinical, radiological, and pathological data enhances diagnostic precision (7). Nevertheless, there exists a research gap in understanding the discordance rates between radiological and pathological diagnoses and how this impacts treatment decisions and prognosis, especially in resource-limited settings where access to multidisciplinary teams may be constrained.

Moreover, earlier studies have focused predominantly on idiopathic pulmonary fibrosis (IPF), with limited data exploring the full radiopathological spectrum across diverse ILD subtypes. There is also a lack of large-scale studies examining the accuracy and outcomes of radiology-based diagnoses in settings where pathology confirmation is not feasible. This gap underscores the need for studies that investigate the extent of radiopathological concordance and the diagnostic value of integrated approaches in the broader spectrum of ILDs.

The aim of this study is to analyze the radiopathological patterns of various interstitial lung diseases and evaluate the concordance between imaging findings and histopathological diagnoses using a multidisciplinary framework. It seeks to assess how integration of clinical, radiological, and pathological inputs can enhance diagnostic accuracy, reduce misclassification, and inform management strategies in ILD patients.

This retrospective observational study was conducted in the Departments of Pathology and Radiology, over a period of 24 months. A total of 75 patients clinically suspected to have interstitial lung diseases (ILDs) were included in the study. The study received prior approval from the Institutional Ethics Committee.

Inclusion criteria were patients with:

• Clinical suspicion of ILD referred for high-resolution computed tomography (HRCT) of the chest,
• Histopathological evaluation by lung biopsy (surgical or transbronchial cryobiopsy),
• Complete clinical, radiological, and pathological data available for multidisciplinary discussion.

Exclusion criteria included:

• Inadequate biopsy samples,
• Incomplete clinical or imaging records,
• Patients diagnosed and treated elsewhere without complete data accessibility.

Radiological Assessment

All 75 patients underwent HRCT scans, which were reviewed independently by two experienced radiologists. The imaging findings were categorized into recognized patterns including usual interstitial pneumonia (UIP), nonspecific interstitial pneumonia (NSIP), organizing pneumonia (OP), hypersensitivity pneumonitis (HP), and unclassifiable patterns, based on established criteria (Raghu et al., 2018). Discordant cases were reviewed jointly until consensus was reached.

Histopathological Evaluation

Lung tissue samples obtained via video-assisted thoracoscopic surgery (VATS) or transbronchial cryobiopsy were fixed in 10% formalin and processed using standard hematoxylin and eosin staining. Two pathologists with expertise in pulmonary pathology independently reviewed the slides. Histological patterns were classified based on American Thoracic Society/European Respiratory Society guidelines (Travis et al., 2013). Immunohistochemistry was applied selectively in cases with diagnostic ambiguity.

Multidisciplinary Discussion (MDD)

After independent evaluations, a multidisciplinary meeting was conducted including pulmonologists, radiologists, and pathologists. Clinical data, imaging findings, and histopathology were integrated to arrive at a final consensus diagnosis for each case. The primary objective was to assess the concordance between radiological patterns and histopathological diagnoses and determine the diagnostic value added by the MDD.

Statistical Analysis

Data were compiled using Microsoft Excel and analyzed with SPSS software. Concordance between HRCT and histopathology was evaluated using Cohen’s kappa coefficient (κ). Descriptive statistics were used to summarize demographic and clinical characteristics. A p-value of <0.05 was considered statistically significant.

Table 1: Baseline Clinical and Demographic Characteristics of ILD Patients (n=75)

This table 1 summarizes the key clinical and demographic features of the 75 patients included in the study. The mean age of the study population was 56.32 years with a standard deviation of 9.64 years, indicating a predominantly middle-aged cohort. Pulmonary function tests showed a mean forced vital capacity (FVC) of 66.92% and a mean diffusion capacity for carbon monoxide (DLCO) of 56.32%, reflecting moderate impairment in lung function typically seen in interstitial lung disease. The gender distribution was skewed toward males (64%). A majority of patients were non-smokers (58.67%). In terms of symptom duration, most patients presented between 6–12 months of symptom onset (41.33%), with 32% reporting symptoms for more than a year, suggesting a chronic disease course at the time of diagnosis.

Table 2: Comparison of Radiological, Histopathological, and Final Multidisciplinary Diagnoses in ILD Patients (n=75)

This table 2 compares the diagnostic distribution of interstitial lung diseases (ILDs) across three key stages: radiological assessment, histopathological evaluation, and final diagnosis following multidisciplinary discussion (MDD). Usual interstitial pneumonia (UIP) remained the most common pattern across all three stages, increasing slightly from 28 cases on radiology to 30 after MDD (40%), reflecting consensus refinement. Nonspecific interstitial pneumonia (NSIP) showed close alignment between pathology (26.67%) and MDD (25.33%), despite being underrepresented radiologically (24%). Organizing pneumonia (OP) and hypersensitivity pneumonitis (HP) had relatively stable distributions, indicating consistency between modalities. Notably, the proportion of unclassifiable patterns decreased from 9.33% on imaging to 6.67% after MDD, demonstrating the value of integrated diagnostic evaluation in reducing ambiguity.

Table 3: Final Diagnostic Shift after Multidisciplinary Discussion in ILD Patients (n=75)

This table 3 summarizes the changes in diagnostic categorization of ILD patients before and after multidisciplinary discussion (MDD). Usual interstitial pneumonia (UIP) cases increased from 28 to 30 following MDD, reflecting a 7.14% improvement in identification due to integrated review. Similarly, NSIP diagnoses increased slightly by one case (5.56%). No change was observed for organizing pneumonia (OP), indicating strong initial radiological-pathological agreement. In contrast, hypersensitivity pneumonitis (HP) and unclassifiable cases saw a reduction of 1 and 2 cases respectively, with unclassifiable diagnoses dropping by 28.57%.

Table 4: Diagnostic Accuracy of Radiological Assessment Compared to Histopathology in ILD Patients (n=75)

This table 4 presents the diagnostic performance of radiological evaluation for different ILD patterns, using histopathological diagnosis as the reference standard. Usual interstitial pneumonia (UIP) showed high sensitivity (92.31%) and negative predictive value (95.74%), indicating its strong detection capability and reliability in ruling out disease when radiological findings are negative. Nonspecific interstitial pneumonia (NSIP) also demonstrated balanced accuracy with both sensitivity and specificity at approximately 85–95%. Organizing pneumonia (OP) and hypersensitivity pneumonitis (HP) had high specificities (98.44% and 93.85%, respectively), though HP showed a relatively lower positive predictive value (66.67%), suggesting a tendency for overdiagnosis on imaging. Unclassifiable ILDs had high specificity (98.51%) and NPV (97.06%), reflecting the cautious and exclusionary nature of this category in radiology.

Table 5: Inter-method Diagnostic Agreement between Radiology and Pathology in ILD Patients

This table 5 presents the degree of agreement between radiological and histopathological diagnoses in patients with interstitial lung disease, measured using Cohen’s Kappa (κ). A κ value of 0.50 indicates moderate agreement, suggesting that while there is some consistency between imaging and biopsy findings, discrepancies remain significant. The results emphasize the importance of multidisciplinary discussion (MDD) in improving diagnostic alignment and clinical confidence in ILD evaluation.

The diagnosis and classification of interstitial lung diseases (ILDs) require nuanced interpretation of radiological and histopathological findings. This study evaluated 75 cases with suspected ILD through a multidisciplinary framework, assessing radiological patterns, histopathological correlations, and the final diagnoses achieved after multidisciplinary discussion (MDD). The integration of imaging, pathology, and clinical findings aimed to improve diagnostic accuracy, reduce ambiguity, and align decision-making with international best practices.

The most common radiological and histopathological subtype identified was Usual Interstitial Pneumonia (UIP), accounting for 37.33% and 34.67% of cases, respectively. This finding aligns with prior studies that underscore the predominance of UIP in ILD cohorts, especially in idiopathic pulmonary fibrosis (IPF) (8, 9). Similarly, the distribution of NSIP (24% radiologically; 26.67% histologically) and OP (13.33% radiologically; 14.67% histologically) showed good correspondence, suggesting reasonable diagnostic consistency. However, discrepancies were notable in hypersensitivity pneumonitis (HP) and unclassifiable cases, reaffirming the challenges of relying on radiology alone in ILD subtypes with overlapping features which is in agreement with earlier study (10).

The Cohen’s Kappa value for agreement between radiological and pathological diagnoses was 0.50, indicating moderate agreement. This level of concordance is consistent with findings by Flaherty et al. (2004), who reported κ values ranging from 0.38 to 0.69, and Walsh et al. (2016), where inter observer agreement improved from fair/moderate levels through MDD. These moderate levels reflect real-world diagnostic complexity, where imaging may not capture the full histological landscape, especially in early-stage or mixed-pattern disease. Importantly, this study demonstrated that Multidisciplinary Discussion (MDD) improved diagnostic clarity. Following MDD, diagnosis changed in 18.6% of cases, with the greatest reduction seen in unclassifiable patterns (from 7 to 5 cases). This supports existing literature that advocates MDD as a critical step in ILD workup. The American Thoracic Society/European Respiratory Society guidelines recommend MDD as the diagnostic gold standard, especially in cases with non-definitive HRCT findings (11). Biglia et al. (2019) also highlighted that MDD not only increases diagnostic agreement but also impacts patient management and outcomes (12). When assessing diagnostic performance, radiology showed strong sensitivity and negative predictive values for UIP (92.3%, 95.7%) and NSIP (85%, 94.5%), suggesting high reliability in ruling out these conditions when findings are absent. However, HP had a relatively lower PPV (66.7%), indicating a higher chance of radiological over diagnosis, likely due to shared features with NSIP or OP. This is corroborated by prior studies, such as Sanduzzi et al. (2023), which emphasize the histological overlap in ILDs and the importance of clinical context (13). Additionally, baseline demographics in our cohort were reflective of other ILD registries, with a male predominance (64%) and mean age of 56.3 years. The average pulmonary function tests (FVC 66.9%, DLCO 56.3%) also align with findings in moderate-to-severe fibrotic ILD populations (14).

Overall, this study reinforces that while HRCT provides valuable insights, it cannot fully substitute tissue evaluation, especially in atypical or borderline cases. The incorporation of MDD significantly enhanced diagnostic precision, reduced misclassification, and shifted diagnostic decisions toward more defined clinical categories.

This study demonstrates that moderate agreement exists between radiological and histopathological assessments in ILD diagnosis, with a Cohen’s Kappa of 0.50. However, the introduction of multidisciplinary discussion significantly improved diagnostic confidence and reduced ambiguity, particularly for unclassifiable and borderline cases. Radiological evaluation showed high sensitivity and NPV in major ILD subtypes, especially UIP and NSIP, but lower PPV for HP indicates the risk of misclassification without histopathological correlation. These findings validate the role of MDD as the cornerstone of ILD diagnosis and reinforce current international recommendations. Continued collaboration between pulmonologists, radiologists, and pathologists remains crucial for optimizing diagnostic accuracy and guiding appropriate treatment decisions in ILDs.

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