A new framework for pulmonary nodules: how terminology impacts management

The Fleischner Society recently updated its Glossary of Terms of Thoracic Imaging, proposing a new approach in the assessment of pulmonary nodules. These updates include changes in terminology regarding the definition of nodule size, as well as inclusive terminology to provide a more flexible framework in the assessment of pulmonary nodule morphology. The broad categories "simple" and "complex" are introduced for more versatile characterization to encompass the wide nodule structure and morphology we see in clinical practice, beyond the classic trichotomy of solid, subsolid, and part-solid. Another key aspect in the assessment of pulmonary nodules includes longitudinal evaluation, a small part of which is growth, namely changes in nodule size. While there is a strong focus on changes in size, other features, such as changes in components, also play a key role in nodule assessment. These include transition in morphology and structure: from simple to complex, and complex to simple; in regard not only to the core of the nodule, but also to borders and contours. This paper examines how the updated terminology aligns with and impacts management within the current nodule management paradigms. KEY POINTS: Question The updated Fleischner Society Glossary of Terms introduces a new definition for nodule size and terminology regarding nodule morphology, and these features are tied to management. Findings Nodule size and morphology are important factors in characterizing and assessing the malignant potential of pulmonary nodules. Clinical relevance The increased threshold for nodule size aims to decrease the workup of small, likely benign nodules. New terminology on morphology allows more flexible characterization to address the broad range seen in clinical practice and offers an opportunity for incorporation in nodule management systems.