GLANDULAR ODONTOGENIC CYST OR LOW-GRADE MUCOEPIDERMOID CARCINOMA? A CASE CHARACTERIZED WITH OVERLAPPING HISTOMORPHOLOGICAL FINDINGS

Abstract

Background Glandular odontogenic cyst (GOC) is a rare odontogenic epithelial cyst of the jaw, with glandular differentiation. It occurs in adults and mostly in the anterior mandible. Case A 38-year-old female patient underwent curettage because of a well-circumscribed 15 × 10 mm cystic lesion, associated with the molar tooth root, in the mandible. Histopathologic examination revealed a neoplastic cystic lesion containing distorted small glands that seemed smaller in size around the cyst lined by mucinous columnar epithelium. In rare areas, immature metaplastic squamous epithelial islands in relation to the wall of the cyst was striking. There were often goblet cells within the cyst lining. No significant nuclear atypia was detected in the epithelium. Very rarely, typical mitoses were observed. Free mucin ponds were commonly observed in the cyst lumen, stroma. PanCK stain highlighted much smaller glands in areas around the cyst, as well as small clusters of epithelial cells in abortive, distorted character and even without gland structure. No significant staining was detected with P53 and Ki67. The case was considered to be compatible with GOC due to lack of nuclear atypia, low mitotic and Ki67 index, and no evidence of destructive invasion. However, because low-grade mucoepidermoid carcinoma could not be excluded, follow-up was recommended. Conclusions GOC has histomorphological findings overlapping with those of low-grade mucoepidermoid carcinoma. The absence of nuclear atypia, mitotic activity, and invasion findings is important in the diagnosis of GOC, but LGMECs that have weak criteria for malignancy may cause serious problems in differentiation from GOCs in some cases.