[Solitary pulmonary nodule on CT - observation or surgical resection?]

Incidentally found solitary pulmonary nodules (SPN) are increasing due to liberal use of high resolution CT scans. SPNs are defined as densities up to 3cm without associated enlarged lymph nodes. Morphologic patterns of the SPN in CT or dynamic changes in serial investigations as well as the individual risk profile (age, smoking history, current or past malignant disease) are crucial to classify the likelihood of malignancy as low, intermediate or high. Whereas low risk SPNs have to be observed by serial CT scans, intermediate risk SPNs have to be evaluated by transthoracic or bronchoscopic biopsies. However, these investigations are only reliable if malignant or specific benign diseases can be clearly diagnosed in the obtained tissue. In all the other cases, SPNs remain undetermined and surgical resection is mandatory. Increasingly, FDG-PET is performed in patients with intermediate risk SPNs and a high risk for surgery aiming to further determine the pre-test probability of malignant disease. Its sensitivity is about 80%. Nodules with high FDG uptake are suspect to be malignant and surgical removal is indicated. SPN with a high likelihood to be malignant are usually resected surgically as a primary approach. In case of metastasis, excisional biopsy may be therapeutic. The surgical method of choice is the video assisted thoracoscopic (VATS) wedge resection. Ideal for this method are nodules of 1 to 2 cm in diameter not localised deeper within lung parenchyma than its own diameter. If a SPN is diagnosed intraoperatively to be a non-small cell lung cancer, anatomic resection can be performed under the same anaesthesia. SPNs diagnosed to be cancer often are early stage tumours. Therefore, lobectomy and lymphadenectomy can also be made in VATS technique. In rare cases, diagnostic thoracotomy may still be necessary to definitely determine the aetiology of a SPN. An interdisciplinary approach is crucial to plan an efficient and individualised work-up of SPNs.