Figure 4. Pathological examination of the anomalous fistula A: tubular structure of cartilage and muscle, lined with stratified squamous epithelium, pseudostratified columnar ciliated epithelium and submucosal glands, inflammatory infiltration of lymphocytes in the mucosal lamina propria (HE stain, ×100); B: glandular hyperplasia, dominated by mucus glands. Mucus exuded into the periductal interstitial space (HE stain, ×100).