[A benign tumor of the cavum: Thornwald's cyst]

The non neoplastic diseases of the nasopharynx are uncommon especially in adults. Cyst of pharyngeal bursa or Thornwald cyst are located in the supero-posterior nasopharynx, in the location of the normal pharyngeal bursa which open into the pharyngeal mucosa. When it persists, a cyst can develop if the orifice becomes occluded. The have a characteristic and distinctive C.T. and N.M.R. aspects, as presented in this paper, well circumscribed round midline mass, sparing muscles lateral as well as posterior, with an high signal in T1 and T2 N.M.R. sequences. No discussion with other pathologic conditions is useful because carcinoma, adenoid and pharyngeal polyp, or Killian's polyps haven't this configuration.