An apical granuloma with epithelial integument

A chronic periapicalesion--apical granuloma--of the first left maxillary molar, which had rarefied the bony plate and grown into the maxillary sinus, was observed in a 64-year-old white male patient. Light microscopic study of the epon-embedded specimen showed a lesion that had been infiltrated predominantly by mononuclear cells and that had isolated neutrophil-dominated foci. The lesion contained extensive networks and arcades of proliferating epithelium. Unlike the classic granulomas of the periapex, which are generally delimited by a well-developed connective tissue capsule, this particular lesion was lined with epithelial tissue consisting of ciliated columnar and stratified squamous components. While the former seemed to be an extension of the sinus epithelium, the latter appeared to be an outgrowth of the proliferating epithelium encountered within the lesion.