A chest X-ray was ordered in a 40-year-old woman due to an acute cough, showing an enlarged mediastinal silhouette (figure 1A). A physical examination showed a body mass index of 26 kg/m2. She reported prior use of hormonal contraception. CT scanning led to the detection of two posterior mediastinal, paravertebral and cystic images (figure 1B): a right, 28-mm-wide cyst at T5–T6 and a left, 24-mm-wide cyst at T4–T5. On MRI (figure 1C), they appeared as two extraspinal, extrapleural, thin-walled, uniloculated cystic lesions, unrelated to the intervertebral foramen.

(A) Posterior anterior chest X-ray showing mediastinal enlargement with bilateral widening of paravertebral lines (arrows). (B) CT scan with contrast (coronal view) reveals two paravertebral, bilateral, low-density, well-defined lesions at T4–T5 and T5–T6. (C) T2-weighted MRI of the dorsal spine (coronal view) …