Primary Presacral Neuroendocrine Tumor Presenting as Multiple Liver Metastasis: A Case Report

Objective: Rare diseaseBackground: Various neoplasms, including neuroendocrine neoplasms (NENs), can arise from the presacral space. Most pre-sacral lesions are detected due to symptoms arising from tumor growth. However, diagnosing small, asymp-tomatic presacral tumors is challenging because of their unique location.Case Report: A 63-year-old woman with chronic hepatitis C underwent follow-up after achieving a sustained virological re-sponse. Abdominal ultrasonography revealed multiple new hyperechoic masses in the liver. Physical and lab-oratory examinations, including tumor marker analysis, yielded unremarkable results. Computed tomography (CT) and magnetic resonance imaging (MRI) indicated metastatic liver tumors but failed to identify the prima-ry site of these lesions. The hepatic mass was biopsied, leading to a diagnosis of grade 2 neuroendocrine tu-mor. 111In-pentetreotide somatostatin receptor scintigraphy revealed significant radiotracer accumulation in multiple hepatic masses, several bones, and a small presacral space lesion. Pathological examination of the presacral lesion confirmed a grade 2 neuroendocrine tumor, similar to the hepatic mass. Review of a CT scan performed 4 years earlier indicated a small cyst-like lesion in the presacral space suspected of being a devel-opmental cyst; however, the presence of cystic components was not confirmed pathologically. The patient was diagnosed with a primary presacral neuroendocrine tumor, which might have originated from a developmen-tal cyst, with multiple liver metastases. Chemotherapy with everolimus was initiated, and the clinical course has been uneventful.Conclusions: We report a rare neuroendocrine tumor arising from the presacral space with multiple liver metastases. The presacral space should be examined when a NEN with an unknown primary site is found.