SLC6A2 and schwannoma: ,2 However, physiological adrenal uptake exists, and false positives have been reported in non-PPGL adrenal lesions such as adrenocortical adenoma, schwannoma, and adrenocortical carcinoma.3, 4, 5 Proposed mechanisms include norepinephrine transporter (NET)-mediated uptake, vesicular monoamine transporter (VMAT)-mediated sequestration into neurosecretory granules, and passive diffusion related to increased tumor vascularity.6, 7, 8