Precancerous lesion and early carcinoma of the pyriform sinus.

Thirty-five specimens from total laryngopharyngectomy clinically diagnosed as squamous cell carcinoma of the pyriform sinus were studied. Patients receiving chemotherapy or radiotherapy were excluded. Pathological examinations revealed 26 (74.3%) precancerous lesions and early carcinoma of the pyriform sinus. Eight out of 26 cases were detected by gross examination. Most pathological findings were carcinoma in situ (CIS). Epithelial changes of the pyriform sinus were not similar to those of the uterine cervix. They usually showed abrupt change, frequently from normal to CIS, mild dysplasia to invasive carcinoma and these lesions can be detected early by physical examination. Because of multifoci of carcinoma, the concept of "multicentric origin" is proposed.