A biopsy after maxillary molar extraction shows pseudostratified ciliated columnar (respiratory) epithelium with a chronic inflammatory infiltrate. This indicates:

Correct answer: A. Maxillary sinus (Schneiderian membrane) lining — i.e., an oroantral communication

• A. Correct. Pseudostratified ciliated columnar epithelium is respiratory epithelium of the maxillary sinus (Schneiderian membrane) — finding it after maxillary molar extraction points to sinus involvement / oroantral communication.
• B. SCC shows dysplastic STRATIFIED SQUAMOUS epithelium, not ciliated respiratory lining.
• C. OKC has a parakeratinized stratified squamous lining with a palisaded basal layer.
• D. Pyogenic granuloma is vascular granulation tissue, not respiratory epithelium.