Odontoma in an Elkhorn Sculpin Alcichthys elongatus Caught in the Sea of Japan

Abstract

A prominent odontoma was found projecting from the maxilla of an elkhorn sculpinAlcichthys elongatus, 27.4 cm in total length, captured in a trap for boreal whelk set offshore from Toyama Bay, the Sea of Japan, in late June, 2002. Microscopic examination of large spherical tumor (29 mm in diameter, 19 mm in depth and 6.5 g in weight) protruding well outside the mouth cavity revealed it to be surrounded by squamous epithelium containing numerous dental tissue masses (imperfect teeth or teeth germ) throughout the stromal tissue. The teeth germ comprised odontoblasts, predentin and calcified dentin. No enamel (substantia adamantia) was demonstrated, although several fragments of calcified trabecular (spongy) bones were encountered. This type of tumor, diagnosed as a compound odontoma, seems to be the first report of such from a teleost from Asian-Oceanic waters. The cause of the tumor is unknown.