CT of the oropharynx, tongue base, and floor of the mouth: normal anatomy and range of variations, and applications in staging carcinoma.

CT scans of 35 patients were obtained during rapid drip infusion of contrast material to determine the range of normal variation in the structures of the oropharynx and the floor of the mouth. Superficial structures such as the tonsillar pillars and lingual and faucial tonsils vary so much in appearance that they are not useful indicators in the detection of subtle lesions; in fact, they are potential sources of "pseudomasses." Asymmetric obliteration of the parapharyngeal space is useful for the detection of subtle lesions of the upper tonsillar fossae; however, confident diagnosis in regard to the lower oropharynx depends on visualization of a mass lesion or loss of the more constant planes in the floor of the mouth and the tongue base. CT findings added unique and valuable information in eight of 12 cases of carcinoma, confirmed the clinical impression of the extent of the lesion in four cases, and were potentially misleading in one case. CT is a valuable adjunct to the detection and staging of an oropharyngeal malignancy.