A biopsy result showed pseudostratified epithelial lining with inflammatory cells. This tissue was part of:

PSEUDOSTRATIFIED CILIATED COLUMNAR EPITHELIUM (PSCC epithelium, aka respiratory epithelium) with inflammatory cells is the NORMAL lining of the MAXILLARY SINUS. When a biopsy from a periapical region shows this type of epithelium with inflammation, it indicates the lesion had penetrated or was adjacent to the MAXILLARY SINUS. An apical cyst is lined with non-keratinizing stratified squamous epithelium. OKC has parakeratinized squamous epithelium. B is correct.