Legume-associated residual cyst.

This report describes three unique cases of residual cyst (RC) which were characterized by large legume implants. To determine whether these represented a distinctive RC subset or if implanted materials have general importance in RC pathogenesis, a retrospective comparison of these cases and 37 further RCs with 40 control periapical cysts was performed. The frequency of foreign material implantation and the associated histopathologic features were assessed. No significant differences were noted suggesting that foreign implantations do not have an etiologically significant association with RCs and that the legume-associated RCs represent a unique subgroup. The relationship of the legume-associated RCs to the category of lesions variously termed giant cell hyaline angiopathy, oral pulse granuloma or hyaline ring granuloma is discussed.