From the Guidelines
A fissural nodule is a small, solid mass or growth that develops within the fissures of the lungs, typically representing a benign lesion such as an intrapulmonary lymph node. These nodules are frequently discovered incidentally during chest imaging studies like CT scans performed for other reasons. Most fissural nodules do not require specific treatment unless they show concerning features such as rapid growth or irregular borders, as noted in the guidelines for management of incidental pulmonary nodules detected on CT images: from the Fleischner Society 2017 1. The appearance of these nodules can sometimes mimic more serious conditions like lung cancer, so radiologists look for specific characteristics to differentiate them from malignant lesions. These characteristics include a triangular or oval shape, smooth borders, and stable size over time, as described in the British Thoracic Society guidelines for the investigation and management of pulmonary nodules 1. Some key features that suggest a benign nature include:
- A perifissural or juxtapleural location
- A morphology consistent with an intrapulmonary lymph node
- A fine linear septal extension to the pleura
- No history of cancer
- No spiculated border or displacement of the adjacent fissure. If a fissural nodule has suspicious features, follow-up imaging or occasionally a biopsy may be recommended to confirm its benign nature, as suggested by the Fleischner Society guidelines 1. Understanding that most fissural nodules are benign can help reduce unnecessary anxiety when they are discovered during routine imaging. In general, the management of fissural nodules should be guided by the principles outlined in the Fleischner Society guidelines, which prioritize a conservative approach for nodules with benign characteristics, while recommending further evaluation for nodules with suspicious features 1.
From the Research
Definition of Fissural Nodule
- A fissural nodule, also known as a perifissural nodule (PFN), is a type of lung nodule that is located adjacent to a fissure in the lung 2, 3, 4.
- Fissural nodules are often found in current or former heavy smokers who undergo computed tomography (CT) for lung cancer screening 2, 4.
Characteristics of Fissural Nodules
- Fissural nodules are typically triangular or oval in shape, and are often located inferior to the carina 2.
- They usually have a septal connection and a mean maximal length of around 3-4 mm 2, 4.
- Fissural nodules can show growth rates similar to those of malignant nodules, but are often benign 4.
Malignancy Potential of Fissural Nodules
- Studies have shown that the malignancy potential of fissural nodules is low 2, 3, 4.
- None of the fissural nodules in the studies reviewed were found to be malignant during follow-up 2, 3, 4.
- The presence of a fissural nodule does not necessarily indicate lung cancer, and further evaluation is often not required 2, 3, 4.