Six cases of so-called maxillary sinus mucous retention cysts are reported here, focusing mainly on X-ray CT and rotational panoramic examinations. The originating wall and the CT number of the lesions are studied.
The results are as follows:
1. Alternate positioning of the patient in the CT examination seemed to present valuable information on the origin and the contents.
2. The probability of occurence seemed to be more than previously reported because three mucous retention cysts were found during CT examination.
3. Mucous retention cysts seem to originate from all of the walls of the maxillary sinus except the upper with equal probability.
4. According to the CT number, the mean value seemed to be around 80. There seemed to be a tendency for small mucous retention cysts to have a rather large CT number.
It is also reconfirmed that the CT examination seems to be valuable for diagnosing the diseases occuring on the maxillary sinus.
