Transmission electron microscopy revealed the presence of Charcot-Leyden cr
ystals within a periapical lesion, which was assessed histopathologically a
s consistent with a periapical granuloma that failed to resolve after conve
ntional endodontic treatment. This paper presents the clinical, radiographi
c, histological, and ultrastructural findings of this case and discusses th
eir potential clinical significance.