Primary ovarian neuroendocrine carcinoma expressing substantially intense ¹⁸F-FDG uptake: A case report

Ovarian neuroendocrine carcinoma is a rare and aggressive tumor with a poor prognosis. Ultrasonography, computed tomography (CT), and magnetic resonance imaging (MRI) are often used for diagnosis. However, no specific features exist, and preoperative diagnosis is often difficult. We present a case in which ovarian neuroendocrine carcinoma was diagnosed postoperatively, with the intention to discuss its imaging features on ¹⁸F fluoro-deoxy-glucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT). A 70-year-old woman presented to a local hospital with abdominal pain. CT showed a uterine mass and multiple swollen lymph nodes. The mass expanded from the uterus into the left ovarian vessels on dynamic MRI. The SUVmax of the mass and lymph nodes on ¹⁸F-FDG PET/CT were notably elevated to 53.2 and 33.0 respectively. Considering the tumor location and high SUVmax, a malignant uterine tumor was suspected. Total abdominal hysterectomy, bilateral salpingo-oophorectomy, omental biopsy, and resection of the left ovarian vessels were performed. Histological examination confirmed that the tumor was a neuroendocrine carcinoma derived from the left ovary. To the best of our knowledge, there are only few reports on the ¹⁸F-FDG uptake in ovarian neuroendocrine carcinomas. Conversely, in other organs, the carcinomas frequently exhibit markedly elevated SUVmax on ¹⁸F-FDG PET/CT. It is possible that ovarian neuroendocrine carcinomas share similar traits, and elevated SUVmax could indicate the potential presence of this histological type.