Presentation
Incidental finding. Patient asymptomatic.
Patient Data
A well-defined soft tissue mass in the right paravertebral location. The soft tissue mass measure 16 x 8 x 18 mm and is located in the right paravertebral location at the sixth level of the thoracic vertebra. There is no bone destruction, no spiculation and no evidence of infiltration into the lungs. There is no mediastinal or axillary lymph node enlargement.
The right paravertebral lesion on the CT is of cystic nature on the MRI sequences; the T2-weighted image shows a homogeneous lesion with a high-intensity signal. There is no evidence of erosion of any adjacent structure.
Pathology report
Macroscopically: Cyst lined by a smooth, glistening pink-red surface.
Microscopically: ciliated columnar-type cells with focal areas of Mullerian-type epithelium with secretory and intercalated-type cells.
Immunohistochemical stains for estrogen receptor (ER), PAX8, and Wilm's Tumor 1(WT1) diffusely positive, consistent with Hattori cyst.
Case Discussion
Cystic lesions can be occasionally be found in the mediastinum, and typically include bronchogenic cysts, esophageal duplication cysts, and neurenteric cysts. In 2005, Hideo Hattori described a cyst of probable Mullerian origin arising in the posterior mediastinum. This cyst was then named Hattori cyst. The origin of cysts of Hattori is unknown. The radiologic differential diagnosis included a bronchogenic cyst or esophageal duplication cyst. The etiology of Mullerian cysts arising in the mediastinum is unclear. Several authors have proposed various theories as to their origin. Hattori suggested that the cyst could represent misplaced mesothelium with Mullerian characteristics.
Radiographer: TSRM Fabio Imola