Multimodality imaging of lithopedion in a postmenopausal woman: A case report emphasizing the diagnostic role of noncontrast computed tomography

Lithopedion is a rare sequela of unrecognized extrauterine pregnancy in which a nonviable fetus undergoes calcification and may retain for years, that occurs in approximately 0.005% of entire pregnancies and 1.5%-1.8% among abdominal ectopic pregnancies. We present a case of 62-year-old postmenopausal woman (Para 5) presenting with chronic pelvic pain and progressive abdominal distention secondary to a presumed retention period of approximately 23 years following an unevaluated gestation. Ultrasound demonstrated a large solid, echogenic mass within the pelvis with posterior acoustic shadowing suggesting the presence of fetal bones. Radiographs revealed a calcified fetal skeleton. Noncontrast computed tomography showed features consistent with true lithopedion (14.0 × 9.4 × 6.4 cm) with a femoral diaphysis length of 57.2 mm which corresponded to an approximate early third-trimester gestational age of 30 weeks. Multiplanar computed tomography demonstrated mild extrinsic compression on the urinary bladder dome without luminal obstruction, mural invasion, bowel obstruction, inflammatory fat stranding, or free fluid. Because of the absence of acute complication and patient’s preference to avoid surgery, conservative management was employed with regular outpatient monitoring. This case highlights the importance of noncontrast computed tomography for anatomical characterization with biometry estimation and most importantly for excluding acute complications, therefore guiding safe and individualized conservative management in asymptomatic elderly patients.