Nailfold videocapillaroscopy as a diagnostic clue in interstitial lung disease: differentiating idiopathic from autoimmune patterns in a Caucasian cohort.

Objective

Interstitial lung diseases (ILDs) include idiopathic pulmonary fibrosis (IPF) and autoimmune-related forms such as interstitial pneumonia with autoimmune features (IPAF) and connective tissue disease-associated ILD (CTD-ILD). Nailfold videocapillaroscopy (NVC) is well established in systemic sclerosis (SSc) but remains underused in ILD characterization. This study aimed to evaluate NVC findings in IPF, IPAF, and CTD-ILD.

Methods

This cross-sectional study included 67 Caucasian ILD patients (16 IPF, 13 IPAF, and 38 CTD-ILD, including 21 SSc-ILD). NVC was performed using a digital videocapillaroscope and scored semi-quantitatively (0-3) across six parameters (total score 0-18). Patterns were classified as normal, nonspecific abnormalities, or scleroderma pattern (early, active, or late). Continuous variables were analyzed with one-way analysis of variance and Bonferroni correction; categorical variables with χ² or Fisher's exact test.

Results

The total NVC score increased progressively from IPF (3.2±1.4) to IPAF (4.5±3.2) and CTD-ILD (6.5±3.1; p=0.001). Capillary loss was the only item of NVC significantly different among groups (p=0.006), although all items showed a gradual increase across the spectrum. Scleroderma patterns were observed in 6.3% of IPF, 23.1% of IPAF, and 65.7% of CTD-ILD patients, particularly in SSc-ILD (95.2%). Notably, 81.3% of IPF patients showed nonspecific abnormalities, suggesting subtle microvascular involvement even in idiopathic disease.

Conclusions

NVC demonstrates potential discriminatory value between IPF and autoimmune-related ILD, especially SSc-ILD. The progressive increase in microvascular abnormalities observed from IPF to SSc-ILD suggests a possible contribution of immune-mediated microvascular involvement across different ILD phenotypes. These findings should be considered exploratory and warrant confirmation in larger prospective studies.  NVC may represent a useful adjunct to serological and radiological assessment in ILD diagnostic pathways.