Usefulness of 18F-Fluorodeoxyglucose Positron Emission Tomography for Detecting Ameloblastoma, With Special Reference to Glucose Transporter-1 Expression

Immunohistochemical evaluation of Glut1 in dentigerous cysts, odontogenic keratocysts, and ameloblastoma

Context

Glucose uptake may be considered the rate-limiting step for the growth and metabolism of the cancer cell. Studies on GLUT1 have shown that GLUT1 is involved in cell survival and proliferation in both healthy and pathological circumstances. GLUT1 expression is regarded as one of the crucial elements in the development of local aggressiveness, tumour invasiveness, and metastasis, particularly in malignant tumours. The role of glut1 in odontogenic cysts and tumours has remained uncertain.

Aim

The aim of the study is to assess the expression of Glut1 in dentigerous cysts, odontogenic keratocysts, and ameloblastoma.

Settings and Design

The study was conducted in GSL Dental College. The study design was a resprospective immunohistochemical study.

Methods and Material

Formalin-fixed, paraffin-embedded blocks of histologically confirmed cases (n = 50), 10 cases of odontogenic keratocysts, dentigerous cysts, ameloblastomas solid, ameloblastomas unicystic, and dental follicles each. Brown colour staining was considered as positive staining for GLUT1. Quantitative analysis was performed by counting the number of labelled cells, and semi-quantitative analysis was conducted by assigning immunostaining intensity scores.

Statistical Analysis

Chi-square test was used to compare differences between the groups. A P value of ≤0.05 was considered as statistically significant.

Results

Odontogenic keratocysts and unicystic ameloblastoma showed ≥50% of label cells with strong intensity of staining. Odontogenic keratocysts and solid ameloblastoma showed sub-cellular localisation of staining in the cytoplasm and membrane. Dentigerous cysts exhibited combined nucleus, cytoplasm, and membrane sub-cellular localisation of staining.

Conclusions

The development of ameloblastomas, odontogenic keratocysts, and dentigerous cysts appears to be influenced by GLUT-1. Variation in its expression may aid in explanation of some of the differences in biological activity of these lesions.

Glucose transporter 1 in health and disease

Glucose, a major source of energy for all cells, is transported into cells with the help of glucose transporters (GLUTs). These transporters are of two types, namely sodium-dependent GLUTs and facilitative GLUTs. These transporters are present in a tissue-specific pattern and have substrate specificity. Among these transporters, GLUT1 (facilitative GLUT) is present ubiquitously on all tissues of the body and helps in the basal uptake of glucose. GLUT1 is known to have many physiological functions in the body from the time of implantation of an embryo and is also seen associated with pathologies, including cancers. This review mainly focuses on GLUT1 in physiological and pathological conditions and the recent advances related to its role in cancer development and applications in cancer therapeutics.

Glucose Transporter 1 Expression in Odontogenic Keratocyst, Dentigerous Cyst, and Ameloblastoma: An Immunohistochemical Study

INTRODUCTION

An array of odontogenic lesions manifest in the maxillofacial region with variable presentations. The biological behavior of lesions, such as odontogenic keratocyst (OKC), dentigerous cyst (DC), and ameloblastoma (AM) always invite debate. Glucose transporter 1 (GLUT-1) is proven to be an indicator of metabolic behavior of several benign and malignant neoplasms.

AIM

The purpose of this study was to evaluate the expression of GLUT-1 in OKC, DC, and AM to understand their metabolic behavior.

MATERIALS AND METHODS

Immunohistochemical expression of GLUT-1 was evaluated in each of the 15 cases of OKC, DC, and AM. The number of labeled cells, staining intensity, and membrane or cytoplasmic expressions were the parameters assessed and analyzed using chi-square test.

RESULTS

All cases showed positive GLUT-1 expression: 86.6% OKC showed more than 50% labeled cells followed by DC (40%) and AM (26.5%); 53.3% OKC showed strong intensity in comparison to AM, which showed weak intensity in 53.3% cases; 86.6% of OKCs showed both membrane and cytoplasmic expression followed by DC (40%) and AM (26.6%), whereas 73.3% of AM showed only membrane expression followed by DC (60%) and OKC (13.3%).

CONCLUSION

Odontogenic keratocyst was found out to be more metabolically active followed by DC and AM.

Immunohistochemical expression of glucose transporter 1 in keratin-producing odontogenic cysts

Background

Keratin-producing odontogenic cysts (KPOCs) are a group of cystic lesions that are often aggressive, with high rates of recurrence and multifocality. KPOCs included orthokeratinised odontogenic cyst (OOC) and parakeratotic odontogenic cysts, which are now considered true tumours denominated keratocystic odontogenic tumours (KCOTs). GLUT1 is a protein transporter that is involved in the active uptake of glucose across cell membranes and that is overexpressed in tumours in close correlation with the proliferation rate and positron emission tomography (PET) imaging results.

Methods

A series of 58 keratin-producing odontogenic cysts was evaluated histologically and immunohistochemically in terms of GLUT1 expression. Different data were correlated using the beta regression model in relation to histological type and immunohistochemical expression of GLUT1, which was quantified using two different morphological methods.

Results

KPOC cases comprised 12 OOCs and 46 KCOTs, the latter corresponding to 6 syndromic and 40 sporadic KCOTs. GLUT1 expression was very low in OOC cases compared with KCOT cases, with statistical significant differences when quantification was considered. Different GLUT1 localisation patterns were revealed by immunostaining, with the parabasal cells showing higher reactivity in KCOTs. However, among KCOTs cases, GLUT1 expression was unable to establish differences between syndromic and sporadic cases.

Conclusions

GLUT1 expression differentiated between OOC and KCOT cases, with significantly higher expression in KCOTs, but did not differentiate between syndromic and sporadic KCOT cases. However, given the structural characteristics of KCOTs, we hypothesised that PET imaging methodology is probably not a useful diagnostic tool for KCOTs. Further studies of GLUT1 expression and PET examination in KCOT series are needed to confirm this last hypothesis.

FDG-PET findings of Ameloblastoma: a case report

Introduction

Ameloblastoma is a benign odontogenic neoplasm of the jaw, rarely presenting as a malignant tumor. Although it is very important to discriminate ameloblastoma from ameloblastic carcinoma in order to decide the appropriate operative procedure, this is difficult using conventional CT and MRI.

Case descriptions

We report a case of maxillar ameloblastoma in a 78-year-old man where FDG-PET/CT was useful for making this discrimination. CT demonstrated a 31 × 43 × 46-mm mass in the left posterior maxillary sinus with destruction of its posterior and lateral wall and alveolar bone. MRI demonstrated a hypo- to isointense heterogeneous pattern on T1WI, heterogeneous hyperintensity with a prominent high-signal spot on T2WI, high signal intensity on DWI reflecting restricted diffusion, and strong heterogeneous enhancement. Because FDG-PET/CT showed mild FDG uptake (SUVmax 2.40) by the mass, ameloblastoma, rather than ameloblastic carcinoma, was considered to be the correct diagnosis.

Discussion and evaluation

It appears that ameloblastic carcinoma shows intense FDG uptake, whereas ameloblastoma shows mild or moderate FDG uptake, and only rarely intense FDG uptake. Our experience suggests that FDG-PET/CT may be effective for discriminating ameloblastoma from ameloblastic carcinoma. Especially, in cases showing mild FDG uptake, benign ameloblastoma would seem the most likely diagnosis.

Conclusions

FDG-PET/CT may be useful as an adjunctive modality for diagnosis, treatment planning and surveillance of ameloblastoma and ameloblastic carcinoma.