Background: Granulomas were frequently misdiagnosed as peripheral lung cancers (PLCs) due to their similarities in imaging findings.

This study aimed to establish a classification system based on thin-section computed tomography (TSCT) features for distinguishing granulomas from PLCs.

Methods: From January 2012 to November 2023, 561 granulomas and 561 size-matched PLCs manifested as solid nodules (SNs) were retrospectively enrolled.

Their TSCT features were evaluated and compared.

Based on single or a combination of multiple features, a classification system comprising multiple distinct types with different features was established for differentiation.

Results: Lesions were classified into eight types.

Types I (nodules with satellite lesions) [28.3% vs.2.1%; positive predictive value (PPV), 0.93], II (nodules with halo sign and/or calcification) (16.4% vs.3.0%; PPV, 0.84), III (nodules with a special shape) (7.7% vs.0.5%; PPV, 0.93), and IV (nodules with ill-defined boundary) (8.6% vs.4.3%; PPV, 0.67) were more common in granulomas than in PLCs (each P<0.05); among other well-defined nodules, type V (non-lobulated nodule with smooth margin) (16.0% vs.4.6%; PPV, 0.78) was common in granulomas (P<0.001), while types VI (non-lobulated nodule with coarse margin) (7.8% vs.14.1%; PPV, 0.64), VII (lobulated nodule with vacuole sign) (1.2% vs.13.5%; PPV, 0.92), and VIII (lobulated nodule without vacuole sign) (14.8% vs.57.8%; PPV, 0.80) were more frequent in PLCs (each P≤0.001).

Receiver operating characteristic (ROC) curve analysis showed that types I, II, III, V, VII, and VIII were more effective in differentiation (each P<0.05).

Conclusions: In differentiating pulmonary SNs, those with TSCT features manifested as type I, II, III, or V had a higher possibility of granulomas.

Keywords: Granulomas; lung neoplasms; tomography, X-ray computed

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Key findings

• Satellite lesions, halo sign, calcification, and special shapes are highly indicative of granulomas, while well-defined solid nodules (SNs) with lobulation should raise suspicion for peripheral lung cancers (PLCs), especially those with a vacuole sign.

Spiculation, pleural indentation, and vascular convergence signs alone are not sufficient for differentiating them.

What is known and what is new?

• Recent studies have demonstrated that satellite lesions, halo sign, and calcification are commonly observed features of benign SNs, whereas the presence of lobulation sign, spiculation sign, pleural indentation sign, and vascular convergence sign indicates lung cancers.

• We explored and verified thin-section computed tomography (CT) features that can effectively distinguish granulomas and PLCs, and identified three new special shapes predominantly found in granulomas.

Furthermore, we established a novel classification system to facilitate accurate differentiation between granulomas and PLCs.

What is the implication, and what should change now?

• Based on the key CT indicators, a classification system including eight types with distinct features was developed, which may serve as an effective guideline for differentiating granulomas and PLCs in clinical practice.

Cite this article as: Xu HB, Lv FJ, Ding C, Fu BJ, Li WJ, Yu JQ, Chu ZG.

Exploring and verifying key thin-section computed tomography features for accurately differentiating granulomas and peripheral lung cancers. J Thorac Dis 2025;17(5):2827-2840.doi: 10.21037/jtd-24-1505

Journal: Journal of Thoracic Disease

Source: National Center for Respiratory Medicine