The contribution of conventional nuclear molecular imaging in characterising the nature of a growing solitary pulmonary nodule. Report of a case.

The solitary pulmonary nodule (SPN) is a relatively common imaging finding, often representing a diagnostic challenge. Radiological appearance, growth rate calculation during follow up and probability of malignancy assessment by the Bayes' theorem are widely used for identifying the nature of a SPN. Molecular imaging by fluoro-18 deoxy glucose positron emission tomography has revolutionised non-invasive diagnosis of lung cancer, but the low-cost, widely available conventional nuclear imaging modalities still remain valid in the field. We present a case of a growing SPN in a middle-aged male smoker. Growth rate assessment by sequential computed tomography scans, over a follow up period of five years, was suggestive of benign histology, while Bayesian analysis warranted histological confirmation of the nodule's nature. Imaging by both labelled somatostatin analogue technetium 99m-depreotide ((99m)Tc-depreotide) and thallium 201-chloride was almost exclusive of malignancy. The nodule was excised and histology showed a pulmonary hamartoma. We briefly discuss the relative role of invasive and non-invasive methods, with emphasis in conventional radionuclide molecular imaging, for the identification of the nature of SPN.