[A case of right paratracheal air cyst]

An 87-year-old female was being examined by her primary care doctor during a follow-up of 4 to 5 years after a diagnosis of non-tuberculous mycobacterial infection. An exacerbation of a shadow was suspected on a chest X-ray film, and therefore the patient was referred to our hospital. Her chief clinical symptom was mild occasional coughing, but no clearly abnormal findings were observed on the clinical examination. On chest CT, a cystic lesion was detected in the right posterodorsal side of the trachea at the level of the thoracic aperture, resulting in the diagnosis of a right paratracheal air cyst. Right paratracheal air cyst is a relatively rare disease, but it is believed that such a diagnosis can be made easily based on its localization and the CT findings, and it is a disease to which attention should be paid, which is why we are reporting it.