Endocrine Abstracts

Introduction: Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH) is documented as a pre-malignant condition by the World Health Organisation. Patients with pulmonary nodules typically undergo 5′-¹⁸fluoro-deoxy-D-glucose (FDG) positron emission tomography combined with computed tomography (PETCT) for further diagnostic investigation. DIPENCH is widely accepted as an FDG negative pathology. The purpose of this analysis was to ascertain if there is FDG uptake within DIPNECH lesions and to identify any corresponding variables that contribute to possible uptake.

Method: The data of 7 patients with pathologically confirmed DIPNECH was identified. Retrospective analysis of the PETCT images was conducted and 146 pulmonary nodules studied. Nodule position i.e. lobe, segment and aspect, size, shape and character on CT component using lung window was recorded. The FDG positive nodules were highlighted and the level of FDG uptake on CT attenuated corrected (CTAC) PETCT images with ultra-high definition reconstruction was recorded as maximum standardised uptake value (SUV max), in order to allow us to correlate the dimensional studies to any possible FDG findings.

Results: The analysis of the recorded data showed the mean size of the nodules was 7.9 mm, ranging between 3 and 50 mm and the mode being 5 mm. The mean SUV max value was found to be 3.0 with a range between 0.9 and 7.2 with a standard deviation of 2. The relationship coefficients between the size of the nodules and FDG uptake was calculated to give a Spearman coefficient rank of 0.88 and Pearson’s coefficient of 0.85.

Discussion: In our study the strong positive Spearman and Pearson coefficients demonstrate DIPNECH is reliably an FDG positive condition with the main contributing variable being the size of the nodule. The surrounding literature search demonstrated only case studies, describing variable uptake with common assertion that DIPNECH is an FDG negative pathology. A limitation of our study is that we selected FDG positive resected disease, but the consistent appearance and correlation of size/SUV max in the remaining and stable underlying variable sized focal lung lesions would still support our hypothesis that DIPNECH is an FDG positive condition.