Incidental Detection of Ovarian Cancer as a Solitary Peridiaphragmatic Distant Lymph Node Metastasis without Pelvic Lesions on 18F-FDG PET/CT.

The spreading pattern of ovarian carcinoma is unique and unlike most other cancers, because exfoliated ovarian cancer cells primarily disseminate within the abdominal cavity, which are then transported throughout the peritoneum by physiological peritoneal fluid. An initial manifestation of a solitary peridiaphragmatic distant metastatic lymph node without peritoneal involvement is very rare. This study reports a case with an incidentally found single hypermetabolic mass in the peridiaphragmatic space without a pelvic lesion in the baseline staging 18 F-FDG PET/CT that histologically turned out to be metastatic serous papillary carcinoma due to ovarian cancer. 18F-FDG PET/CT may allow the identification of the initial manifestation of unexpected distant oligometastatic statuses of an unknown primary ovarian cancer.