Objective: We sought to evaluate the incidence and clinical outcome of an accidental finding of actinomycotic colonies in periapical lesions submitted for histologic examination.
Study design: The study included all periapical biopsy specimens submitted for histologic examination between 1997 and 2000. Sections of paraffin-embedded tissues, 5 microm, were cut and stained by using hematoxylin and eosin, periodic acid-Schiff, and the Gram stain. The presence of typical branching colonies of filamentous bacteria staining positive for periodic acid-Schiff and Gram stain was indicative of Actinomyces.
Results: Typical actinomycotic colonies were identified in 17 of 963 (1.8%) periapical biopsy specimens. The mean patient age was 42, and males were predominant (65%). The maxilla was the most frequently involved site (65%), with equal distribution in the anterior and posterior areas. Radiographically, most cases presented as well-demarcated radiolucent lesions. Malignancy was suspected in 3 cases. Of the periapical lesions, 15 were epithelialized, and in 4 cases, a true epithelial-lined lumen was found, which was diagnosed as a radicular cyst. A residual cyst was diagnosed in 1 case, and in 1 case, an epithelial lining was not identified. Treatment included surgical curettage and a short course of antibiotic therapy. Healing was uneventful in all cases.
Conclusions: Periapical actinomycosis is not common. Its outcome is favorable after surgical curettage supplemented by short-term antibiotic treatment. The relationship of periapical actinomycosis with the more serious cervicofacial actinomycosis should be evaluated.