Reactive Lymph Nodes: A diagnostic challenge in Somatostatin Receptor Imaging of Neuroendocrine Neoplasms
DOI:
https://doi.org/10.64149/J.Carcinog.24.4.354-362Keywords:
Neuroendocrine tumors, DOTATOC-PET, Follicular dendritic cells, Somatostatin receptor 2, Reactive lymphadenopathy, PitfallsAbstract
Background: Reactive lymph node changes can present significant diagnostic challenges, particularly in patients with neuroendocrine neoplasms.
Objectives: To investigate the phenomenon where reactive lymph nodes, which are typically benign, mimic the appearance of lymph nodes positive for 68Ga-DOTATOC-PET or SRS.
Methods: Two patients with a history of with neuroendocrine tumors were subjected to DOTATOC-PET, histopathological examination and immunohistochemical analyses. Detailed clinical histories were collected, and the lymph nodes underwent thorough histopathological evaluations to determine the underlying cause of the imaging findings.
Results: Both neuroendocrine neoplasms cases exhibited marked hyperplasia of follicular dendritic cells (FDCs) in the lymph node germinal centers, forming dense somatostatin receptor 2 (SSTR2)-positive meshworks. The SSTR2 on these cells binds 68Ga-DOTATOC, leading to imaging appearances that may mimic metastatic lymph nodes. In one case, the changes were associated with COVID-19 vaccination, and in the other, with chronic pelvic inflammation.
Conclusions: Understanding the phenomenon of DOTATOC-PET positivity due to reactive follicular dendritic hyperplasia is crucial for the accurate interpretation of PET scans in neuroendocrine neoplasm patients. This awareness helps avoid misdiagnosis and unnecessary interventions, highlighting the importance of correlating imaging findings with clinical history and performing thorough histopathological evaluations.
