Osteoblastic bone metastases from neuroendocrine tumor (NET) of unknown origin detected by 18fluorocholine PET/CT and its comparison with 68gallium-DOTATOC PET/CT

RATIONALE Choline (CH) positron emission tomography (PET)/computed tomography (CT) with fluorine 18 (F) CH is increasingly used not only to evaluate patients with biochemically recurrent prostate cancer but also to assess metastatic lesions that are difficult or impossible to identify using more conventional modalities. Our experience with CH PET/CT has shown that it can also be used for many other malignancies. PRESENTING CONCERNS A 71-year-old male with a neuroendocrine tumor (NET) of unknown origin showed osteoblastic bone metastases positive to F-CH PET. INTERVENTIONS Diffuse bone and liver metastases were gallium-DOTATOC PET-positive with only mild uptake on FDG PET/CT. An increased prostate specific antigen (8 μg/L) gave rise to a suspicion of concurrent prostate cancer and the patient underwent F-CH PET/CT which showed diffuse uptake in the bone. A CT-guided bone biopsy confirmed osteoblastic bone metastases from NET. OUTCOMES Given the aggressiveness of the tumor, the patient underwent treatment with temozolomide from July 2015 to December 2015, maintaining stable disease. However, progression was documented in January 2016 and the patient was enrolled onto a phase II peptide receptor radionuclide therapy retreatment trial, which is currently ongoing. MAIN LESSON Our study highlights that NETs should be taken into consideration in the differential diagnosis of osteoblastic bone metastases showing F-CH uptake. A prognostic role for this imaging technique can also be hypothesized.