A corpus luteal cyst masquerading as a lymph node mass on PET/CT scan in a pregnant woman with an anterior mediastinal lymphomatous mass

A 26-year-old woman presented with a history of dyspnea. The patient declined a pregnancy test before undergoing a noncontrast CT scan of the chest that showed an anterior mediastinal mass that was F-18 FDG avid on a subsequent PET/CT. Additionally, PET/CT demonstrated focal uptake in the right adnexal region. Surgical excision of the anterior mediastinal mass revealed Hodgkin lymphoma. A contrast-enhanced CT scan of the chest, abdomen, and pelvis after surgery showed no residual tumor in the mediastinum. An enhancing 1.2-cm round lesion was noted in the right adnexal region. An ultrasound examination revealed a corpus luteal cyst in the right adnexa and an intrauterine pregnancy thus discounting pelvic lymph node involvement. The patient was counseled about radiation exposure. She elected to have a therapeutic abortion and received chemotherapy. This case highlights the need to be cognizant of physiologic changes associated with possible pregnancy.