F-18 Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography Imaging for Diagnosing Ovarian Small Cell Carcinoma of the Hypercalcemic Type

A 19-year-old woman presented with lower abdominal pain. Laboratory results showed elevated levels of ionized calcium, 1.85 mmol/l (1.125–1.250 mmol/l), and total calcium, 3.75 mmol/l (2.1–2.55 mmol/l), but a low level of parathyroid hormone (PTH), 1.2 ng/l (10–57 ng/l). The level of the tumor marker CA-125 was also elevated, measuring 36.3 IU/mL (0–21 IU/mL). Magnetic resonance imaging (MRI) of the abdomen and pelvis revealed the presence of a well-defined, solid, complex adnexal mass (approximately 15？×？12？×？9 cm in size). The mass was solid, with an area of heterogeneously decreased signal on T1-weighted images and increased signal on T2-weighted images (Fig. 1), likely representing necrosis and suggesting the tumor was malignant