P1.03-078 Size Matters...but Don't Underestimate the Power of Morphology

Abstract

The detection of solitary pulmonary nodules has increased due to the widespread use of Computed Tomography (CT) and will increase even more in the future when lung cancer screening will be embedded in daily practice. In addition to the clinical information, size is one of the most important parameters to assess the likelihood of malignancy. Although there is a considerable overlap in imaging characteristics of benign and malignant solitary pulmonary nodules, the power of morphology –even in small nodules- should not be underestimated. The aim of this pictorial essay is to give an overview of the wide range of morphologic characteristics and to address the available evidence on sensitivity and specificity of these characteristics. Cases presented were collected during the Multidisciplinary Thoracic Oncology Tumor Board between January 2014 and May 2016. All malignant cases have histopathologic proof, whereas benign lesions were included when the benign nature was suggested after follow-up, negative PET-scan and/or multidisciplinary consensus. With regard to margin characteristics, spiculation is highly suggestive of a malignant nature. It is the only feature that is incorporated as ‘morphologic’ variable in most risk prediction models. Other features however may also be strong indicators of malignancy. Lobulation, halo sign, pleural indentation, vascular convergence sign and pitfall sign are frequently encountered in malignant nodules. The nodule-bronchus relationship can give additional information regarding the nature of the nodule, with signs such as air bronchogram, bubble like lucencies and bronchus cutoff sign being indicative of a malignant nature. In cavitated nodules, a very thin wall might indicate a benign cause, whereas a very thick wall is more common in malignant nodules. Calcification is typically seen in benign nodules, but depending on the calcification pattern a malignant etiology cannot be excluded. The presence of fat is a relative reliable sign of benignity. Thin-section CT will enable detection of subtle findings. Nodules rarely present with only one characteristic and combination of findings can definitely increase the likelihood of a correct diagnosis. The management of solitary pulmonary nodules involves both clinical and imaging assessment. Although a great overlap exists in morphologic features of benign and malignant nodules, thorough knowledge and recognition of subtle morphologic findings will aid in early detection of nodules with a high likelihood of malignancy and will avoid unnecessary follow-up and delay in diagnosis and treatment.