Cushing syndrome manifested during pregnancy and diagnosed following a fragility fracture of the pelvis.

Cushing syndrome (CS) is a major cause of secondary osteoporosis, and postpartum fractures associated with CS have occasionally been reported. However, fractures occurring during pregnancy in patients with CS are exceptionally rare. Additionally, several cases of adrenal CS that became apparent or worsened during pregnancy have been reported. A 31-year-old pregnant woman developed leg edema, subcutaneous bleeding, and a moon face at 17 weeks of gestation. At 24 weeks, she was diagnosed with a fragility fracture of the left pelvis and was admitted to our hospital. She exhibited cushingoid features that were not present before pregnancy. Endocrinological evaluation revealed elevated serum cortisol, suppressed adrenocorticotropic hormone, disrupted diurnal cortisol rhythm, and markedly elevated 24-h urinary free cortisol levels. Abdominal magnetic resonance imaging revealed a 30-mm left adrenal tumor consistent with an adenoma. Based on these findings, a diagnosis of CS due to a left adrenal adenoma was established. Robot-assisted laparoscopic adrenalectomy was performed at 28 weeks and 5 days without complications. Bone mineral density measured postpartum showed severe osteoporosis. This case highlights that adrenal CS may manifest or be exacerbated during pregnancy and increase the risk of various complications, including fragility fractures, emphasizing the importance of early diagnosis and management.