RESUMO
OBJECTIVE: We report the first 4 cases of intraoral nonnecrotizing granulomatous foreign body reactions to diatoms, plausibly as a result of exogenous material introduced following iatrogenic or traumatic injury. STUDY DESIGN: Clinical and histopathologic findings of 4 intraoral cases of nonnecrotizing granulomatous foreign body reaction to diatoms, single-celled algae belonging to the taxonomic phylum Bacillariophyta, are reported. RESULTS: The lesions presented either in the jaws or in the soft tissue overlying the alveolar bone, in some instances mimicking an inflammatory lesion of odontogenic etiology. Microscopically, the lesions presented as nonnecrotizing granulomatous inflammation associated with either spherical and radially symmetric or rectangular and bilaterally symmetric diatomaceous foreign material. CONCLUSION: The diagnosis of a diatom-associated foreign body reaction necessitates familiarization with the histopathologic features of these organisms to accurately characterize the nature of such lesions.