Metaplastic Changes in Odontogenic Cysts of the Jawbone: Their Significance and Relation to MUC Family Expression

Research Article

J Dent & Oral Disord. 2021; 7(1): 1156.

Metaplastic Changes in Odontogenic Cysts of the Jawbone: Their Significance and Relation to MUC Family Expression

Harada H1,2*, Iizuka N1, Nakatsuka SI3, Shima M4, Date E1, Honma K5 and Kurose A2

1Department of Diagnostic Pathology, Kishiwada City Hospital, Japan

2Department of Anatomic Pathology, Hirosaki University Graduate School of Medicine, Japan

3Department of Pathology, Sakai City Medical Center, Japan

4Department of Oral Surgery, Kishiwada City Hospital, Japan

5Department of Diagnostic Pathology and Cytology, Osaka International Cancer Institute Hospital, Japan

*Corresponding author: Hiroshi Harada, Department of Anatomic Pathology, Hirosaki University Graduate School of Medicine, 5 Zaifu, Hirosaki 036-8562, Japan

Received: February 22, 2021; Accepted: March 17, 2021; Published: March 24, 2021

Abstract

Odontogenic cysts are typical diseases that account for the majority of lesions that occur in the jawbone, among which radicular and dentigerous cysts are the most common. In some cases, metaplastic changes in these cysts result in the development of goblet-like mucous cells admixed with ciliated columnar cells. Odontogenic cysts are of little importance to emergent risk in normal conditions, but such histological alterations could be drastic and even confusing. We examined the expression of MUC family in these cystic lesions and investigated their relationship with histomorphological features. 6 cases of radicular and dentigerous cysts with obvious metaplastic changes were studied. Of these, 4 were male and 2 were female. One case occurred in the maxilla and 5 in the mandible. Immunohistochemically, almost the entire epithelium was positive for MUC1 and MUC4 in all cases, and the decapitation-like protrusions on the surface layer showed stronger expression. MUC5AC was selectively expressed in mucous cells, while MUC2 and MUC6 were negative. The lining epithelium with metaplastic changes closely resembled the bronchial epithelium, and MUC expression indicates a potential role in these morphological changes.

Keywords: Radicular cyst; Dentigerous cyst; Mucous cell; Ciliated cell; Metaplasia; MUC

Introduction

Odontogenic cysts are typical diseases that account for the majority of lesions that occur in the jawbone, among which radicular and dentigerous cysts are the most common. As a result of metaplastic changes, both types occasionally display goblet-like mucous cells mixed with ciliated columnar cells. In such cases, the histopathological diagnosis may be complicated by this unusual morphology.

MUC is a general term for the core mucus proteins, and many types have been identified. Several family members are currently used as prognostic factors in various cancer types, but to our knowledge, their expression in odontogenic cysts has not been described except our reports [1,2].

In this study, we examined the expression patterns of five MUC family members in these cystic lesions and investigated their association with histomorphological features of odontogenic cysts.

Patients and Methods

Six cases of radicular and dentigerous cysts with obvious metaplastic changes in four men and two women were extracted from the diagnostic registration files at Kishiwada City Hospital from 2014 to 2018. One case occurred in the maxilla and five occurred in the mandible. The patient age at the time of diagnosis was 36 to 71 years (average, 44 years). Both radicular cysts had developed in relation to the first molars, whereas all four dentigerous cysts were lesions caused by the third molars.

Formalin-fixed paraffin-embedded specimens were used for light-microscopic observation by conventional methods. Samples were fixed in 10% formalin, embedded in paraffin, cut into 4μm-thick serial sections, and used for hematoxylin and eosin stain, and also histochemical stains, such as Periodic Acid–Schiff (PAS) and alcian blue stains on demand.

Immunohistochemical analyses were performed for MUC1, MUC2, MUC4, MUC5AC and MUC6 with similar serial sections. The procedure was performed using the Roche BenchMark ULTRA IHC/ ISH Staining Module (Ventana Medical Systems, USA) according to the manufacturer’s instructions. Data of primary antibodies used for immunohistochemistry was as follows: MUC1 (clone H23, prediluted, Ventana Medical System, USA), MUC2 (clone MRQ-18, prediluted, Sigma-Aldrich Co, USA), MUC4 (clone EPR9308, 1:50 dilution, Abcam, USA), MUC5AC (clone MRQ-19, prediluted, Sigma-Aldrich Co, USA) and MUC6 (clone MRQ-20, prediluted, Sigma-Aldrich Co, USA).

Two specimens of normal oral mucosa excised during the treatment of other diseases were used as control specimens in addition to three radicular and dentigerous cysts without obvious metaplastic changes.

Results

Light-microscopic observation

Histologically, all lesions preserved the basic structure of the cyst and consisted of a cystic wall of fibrous connective tissue and a non-keratinizing stratified squamous epithelium covering the luminal surface (Figure 1a). Inflammatory infiltration in the wall was relatively minor, not only in dentigerous cysts, which are not caused by inflammation, but also in radicular cysts.