[Organized follicular cyst simulating a sinus lesion].

Follicular cyst is a frequent lesion rich in cholesterine and methemoglobin. These cysts produce T1 shortening and a high intensity signal on T1-weighted imaging. The most frequent location is the lower mandibular ramus. Sometimes, it occurs in the maxillar with possible involvement of the paranasal sinuses simulating a mucocele or a space-occupying lesion of the sinus.