Mucinous adenocarcinoma arising from a tailgut cyst: A case report

Figure 3 Microscopic examination confirmed the presence of a cystic mass that comprised thick fibrous bands that divided it into three cystic spaces, the largest of which corresponded to mucinous adenocarcinoma. A: Fibrous tissue separates two cystic spaces, one benign lined by keratinized squamous cell epithelium and the other corresponding to mucinous adenocarcinoma; B-D: Higher magnification of mucinous adenocarcinoma that is immunohistochemically positive (IHC-positive) for antibodies CK20 and CK7; E and F: A smaller cystic space with fibromuscular wall lined by keratinized squamous epithelium and partially by pseudostratified ciliated columnar epithelium (arrow) is observed. Section of the pilonidal cyst (arrow: Hair shaft). [A: Hematoxylin-eosin staining (HE), magnification × 40; B: HE × 100; C: IHC × 20; D: IHC × 100; E and F: HE × 40].