F-18 FDG Accumulation in an Octreotide Negative Merkel Cell Tumor.

Regional positron emission tomography (PET) imaging with F-18 Fluorodeoxyglucose (FDG) was performed in a patient with pathologically proven Merkel cell tumor around the right knee region. Prior to the PET imaging, whole-body Indium-111 octreotide scan was performed in this patient but was negative. F-18 FDG was offered as an attempt to image this somatostatin-receptor negative Merkel cell tumor. The PET images delineate a series of focal abnormal uptake along the right lower extremity without evidence of distant metastasis. Patient was treated locally. The positive accumulation of F-18 FDG in Merkel cells may offer a tool for defining the extent of this rare neuroendocrine tumor.