Perineural Spread of Esophageal Carcinoma

Pathologists frequently observe perineural invasions by carcinomas in routine histological examinations of surgical materials. There have been detailed histological reports of perineural cancer infiltration of the head and neck, prostate, and gallbladder. It has been reported that the perineural spaces are occasionally invaded by oral tumors for a distance of several centimeters [1]. Perineural invasion is considered to be one of the important routes of tumor dissemination in these organs. The conventional belief was that perineural spread occurred through the perineural lymphatics along the peripheral nerves. However, in our previous studies [2] although we could not observe lymphatics along the peripheral nerves in the esophageal walls, perineural invasion was observed histologically in 42 (28%) of a total of 150 surgical cases of esophageal squamous cell carcinoma and in 13 (50%) of the 26 cases in which tumors infiltrated other organs by passing through the esophageal adventitia. Perineural invasion could not be observed in 12 patients examined in whom cancer invasion was limited to the mucosa or submucosa (Table 1). Perineural invasion was observed only in the tunica muscularis propria and adventitia. According to the serial histopathological examinations [3] of 10 cases of perineural spread in the esophageal walls, lesion length ranged from 2.4 to 11.0 mm (mean 6.8 mm). Moreover, the adventitia of the esophagus was found to contain not only many lymphatics and blood vessels, but also many nervous plexuses in the fibroconnective tissue.