Pancreatic neuroendocrine tumor (PNET) is a subgroup of neuroendocrine tumor (NET) that has unique biology and natural history. The histological classification has a major role in the management of this pathology, but in recent years Gallium 68 dotatate (68Ga-DOTA) scanning is at the center of a discussion about how these imaging technologies can modify clinical management of neuroendocrine tumors and how their results are correlated to Ki67 index.
We hereby describe a case of a patient that investigated an unspecific stable pancreatic nodule suspected of high-grade NET after evaluation with 68Ga-DOTATOC positron emission tomography - computed tomography (PETCT) and 18F-Fluorodeoxyglucose (18F-FDG) PETCT.
The images corroborate the hypothesis of high-grade NET based on the standard uptake value (SUV) described in both image exams (16.4 in 18FDG PETCT and 9.2 in 68Ga-DOTATOC PETCT). After surgery, the histopathological analyses revealed a localized grade 2 well differentiated NET, Ki-67 of 4.7, evidencing a rare case of mismatch between the functional image and the in vivo characterization of the neoplasm.
Functional imaging of neuroendocrine tumors with different modalities of PETCT is a well-described strategy for evaluating PNET and can dictate conducts in some cases. However, histopathological analysis is crucial to confirm the grade and prognosis related to this disease. Besides the rarity of this case, our patient presented a mismatch between imaging and histopathological analysis, with the former one allowing active surveillance based on a low-grade neuroendocrine tumor.