Pathogenesis of Mediastinal Paravertebral Müllerian Cysts of Hattori

Hattori reported isolated posterior mediastinal paravertebral müllerian cysts of undetermined pathogenesis in women. We report a 41-year-old woman with a family history of anencephaly, spina bifida, and scoliosis who presented with increasing left-sided mid-thoracic pain uncontrolled by her usual pain medication for symptomatic moderate rotary scoliosis. A magnetic resonance imaging demonstrated a paravertebral saccular lesion at the level of the sixth thoracic vertebra. The 2.1×1.5×1.3 cm T6 paravertebral cyst was excised through a left thoracotomy. The final microscopic diagnosis and immunohistochemistry revealed endosalpingiosis. On the basis of histology, immunohistochemical staining characteristics, and the presence of estrogen and progesterone receptors, we conclude that our patient with a benign mediastinal paravertebral endosalpingiotic müllerian cyst had a lesion identical to those described by Hattori, Thomas-de-Montpreville and Dulmet, and Businger et al. We explain the pathogenesis and thoracic location of posterior mediastinal endosalpingiotic cysts by Ludwig's theory of pathogenesis for the Mayer-Rokitansky-Küster-Hauser syndrome.