Patrícia Carlos Caldeira

Oral leukoplakias with different degrees of dysplasia: comparative study of hMLH1, p53, and AgNOR.

BACKGROUND hMLH1 is one of the major proteins of the mammalian mismatch repair system. It has been suggested that the mismatch repair machinery could be linked to p53, a tumor suppressor protein. The AgNOR technique is used to assess cell proliferation. The aim was to compare the immunoexpression of hMLH1 and p53, and AgNOR number in oral leukoplakias with different degrees of dysplasia. METHODS Sixty-two samples were evaluated by immunohistochemistry for hMLH1 and p53, and AgNOR technique, being 17 without dysplasia, 19 with mild dysplasia, 16 with moderate dysplasia, and 10 with severe dysplasia. RESULTS hMLH1 immunoexpression showed decreasing indexes, while p53 and AgNOR showed increasing indexes from lesions with lower degrees of dysplasia to lesions with more severe dysplasia. An inverse correlation between hMLH1 and both p53 and AgNOR, and a direct correlation between p53 and AgNOR were observed. CONCLUSIONS Alterations in the immunoexpression pattern of hMLH1 and p53 seemed to be early events in oral carcinogenesis. During acquisition of a more dysplastic phenotype, keratinocytes may show diminished capacity of DNA repair and tumor suppression, as well as higher cellular proliferation, and these pathways can be somehow interconnected.

hMLH1 immunoexpression is related to the degree of epithelial dysplasia in oral leukoplakia.

BACKGROUND hMLH1 is a protein of the mammalian mismatch repair system responsible for genomic stability during repeated duplication. Relation between its altered expression linked to microsatellite instability has also been observed in oral leukoplakias (OL) and squamous cell carcinomas pointing to a possible role of hMLH1 in oral carcinogenesis. To our knowledge, this is the first study evaluating the immunoexpression of hMLH1 in OLs regarding their different degrees of epithelial dysplasia. METHODS Sixty-two specimens of OL were classified in four groups: 17 without dysplasia, 19 with mild dysplasia, 16 with moderate dysplasia, and 10 with severe dysplasia. Immunohistochemistry for hMLH1 was performed, and percentage of positive cells was assessed. In the statistical analysis, P values <0.005 were considered significant. RESULTS hMLH1 immunoexpression showed decreasing indexes from lesions with lower degrees of dysplasia to lesions with more severe dysplasia. Statistical difference was found mainly between suprabasal layers and total indexes. CONCLUSIONS hMLH1 immunoexpression was inversely related to the OL degree of dysplasia. The total epithelial hMLH1 index seems to be of more clinical relevance than the evaluation stratified by layers. Our findings also suggest a role of such alterations in this pathway of DNA repair as an early event in oral carcinogenesis.

Correlation between salivary anti‐HCV antibodies and HCV RNA in saliva and salivary glands of patients with chronic hepatitis C

BACKGROUND To investigate the correlation between anti-hepatitis C virus (HCV) antibodies in saliva and detection of HCV RNA in saliva and salivary glands of patients with chronic hepatitis C. METHODS A total of 180 samples of saliva (131 non-stimulated and 49 stimulated) from 133 patients with chronic hepatitis C were tested by ELISA for presence of anti-HCV antibodies. Results were compared with the detection of HCV RNA in saliva and salivary glands samples. Pearsons chi-squared and Fishers exact tests were performed for statistical analysis. RESULTS Anti-HCV antibodies could be detected in 47/180 (26.1%) saliva samples. In 11/47 (23.5%) of these, HCV RNA was also detected. From the 133/180 (73.9%) saliva samples with undetectable anti-HCV antibodies, 49/133 (36.8%) were positive for HCV RNA at least in one saliva sample. From the 64 patients from whom salivary gland samples were available, 17/64 (26.6%) had detectable anti-HCV antibodies in saliva, from which 2/17 (11.8%) also had HCV RNA in the salivary gland. From the 47/64 (73.4%) cases negative for anti-HCV antibodies in saliva, 10/47 (21.3%) were positive for HCV RNA in salivary gland. CONCLUSIONS Taken together, our results suggest that there is no correlation between the presence of anti-HCV antibodies in saliva and the detection of HCV RNA in saliva and salivary glands in patients with chronic hepatitis C. Nevertheless, as there was a statistically significant difference between detection of anti-HCV antibodies and HCV RNA in stimulated saliva, our study points toward the need for new research on mechanisms of HCV shedding in saliva.

Desmoplastic fibroblastoma (collagenous fibroma): a case identified in the buccal mucosa.

Desmoplastic fibroblastoma is a rare, benign, soft tissue tumor affecting mainly the subcutaneous and muscle tissue. Only five cases identified in the oral cavity have been reported in prior literature. This article presents a case report of a 56-year-old man, with no previous history of trauma, who presented a slow-growing mass in the buccal mucosa. Histopathology and immunohistochemistry staining studies were performed, and a diagnosis of the desmoplastic fibroblastoma was made. The patient has been disease-free for one year.

Tumor of the hard palate

At the Oral Diagnosis Clinic at the Dentistry School of Universidade Federal of Minas Gerais, a 29-year-old white woman was admitted with a slow-growing, painless oral lesion that had been present for 1 year. The patient was in her eighth month of pregnancy and was receiving medical treatment for slight iron-deficiency anemia related to the pregnancy. Extraoral examination revealed no other abnormalities. One lobulated, nonulcerated lesion was evident on the right posterior hard palate. It was mainly pink with darkened, reddish and whitish areas. The lesion was well circumscribed and partially sessile with a fibrous consistency; it measured approximately 35 20 mm. Superficial vascularity was evident in some areas (Figure 1, A). Radiographic examination did not reveal evidence of bone involvement (Figure 1, B). Neither the dental caries on the maxillary right first molar nor the periapical lesion on the maxillary left lateral incisor appeared to be associated with the lesion.

Metallothionein immunoexpression in non-syndromic and syndromic keratocystic odontogenic tumour

Background To compare the metallothionein (MT) immunoexpression in non-syndromic and syndromic keratocystic odontogenic tumour (KOT), to correlate MT with cellular proliferation, and to evaluate the influence of inflammation in MT. Material and Methods Fourteen cases of KOT were submitted to immunohistochemistry for MT and Ki-67 analysis. The lesions were grouped according to their grade of inflammation, and statistical analysis was performed. Results MT was higher in non-syndromic KOT than in syndromic KOT (p<0.05). No statistical difference in Ki-67 could be identified; however, an inverse correlation was observed between MT and Ki-67 in both lesions. When analysing inflammation, non-syndromic KOT showed no differences in either MT or Ki-67. Conclusions The MT immunophenotype of syndromic KOT was different from non-syndromic KOT. MT might not be involved in the proliferation control of both KOT. MT and Ki-67 immunoexpressions proved to be unaffected by inflammation in non-syndromic KOT. Key words: Odontogenic tumours, basal cell nevus syndrome, metallothionein, Ki-67 Antigen, immunohistoche-mistry.

Metallothionein immunoexpression in selected benign epithelial odontogenic tumors.

BACKGROUND Odontogenic tumors exhibited variable biologica behaviors. Metallothionein (MT) is correlated with the cellular homeostasis of essential metals, cellular differentiation, and proliferation. The core goals of this study are (i) to report and to compare MT expression among benign epithelial odontogenic tumors; (ii) to correlate MT with cellular proliferation index; and (iii) to evaluate the influence of the inflammatory infiltrate on MT expression. MATERIALS AND METHODS Ten cases of solid ameloblastomas (SABs), 4 squamous odontogenic tumors (SOTs), 5 adenomatoid odontogenic tumors (AOTs), and 3 calcifying epithelial odontogenic tumors (CEOTs) were subjected to immunohistochemical to anti-MT, anti-Ki-67, and anti-PCNA. Statistical analysis was performed using BioEstat(®) 4.0. RESULTS Metallothionein staining was found to be the highest in the SABs (93.1%), followed by SOTs (52.9%), AOTs (38.4%), and CEOTs (0%). MT staining exhibited statistically significant differences between the SABs and the SOTs (P = 0.0047) and the AOTs (P = 0.0022). A weak-to-strong positive correlation between IMT and IK or IP was observed in SABs and SOTs, whereas a strong negative correlation was observed in AOTs. No differences in IMT, IK, and IP were observed between inflammation groups A and B. CONCLUSIONS The increased MT expression observed in the SABs might be correlated with clinical behavior (local invasiveness and high rate of recurrence). In the SABs and SOTs, MT plays a role in the stimulation of cellular proliferation. In contrast, MT can inhibit cellular proliferation in the AOT. The IMT, IK, and IP are not affected by inflammation.

Metallothionein in the radicular, dentigerous, orthokeratinized odontogenic cysts and in keratocystic odontogenic tumor

BACKGROUND Metallothionein (MT) is a protein correlated with cellular differentiation and proliferation, as well as with the inhibition of apoptosis. The aims were to report and to compare the MT expression in odontogenic cysts and keratocystic odontogenic tumor (KOT); to correlate the MT with cellular proliferation; and to evaluate the influence of the inflammation in MT. METHODS Nine cases of radicular cyst (RC), nine dentigerous cyst (DC), four orthokeratinized odontogenic cyst (OOC), and eight KOT were submitted to immunohistochemistry using anti-MT and anti-Ki-67. Indexes of MT (IMT) and Ki-67 (IK) were obtained. Lesions were grouped according to inflammation: mild-to-moderate (group A) and intense (group B). RESULTS IMT proved to be highest in RC (91%), followed by DC (89%), KOT (78%), and OOC (63%). IMT was inversely correlated with IK in KOT, and OCC, but was positively correlated with RC and DC. No differences in IMT and in IK could be observed between groups A and B. CONCLUSIONS The higher IMT found in RC and DC compared to OCC and KOT, as well as the differences between the last ones, is possibly correlated with their different histopathological features and clinical behavior. In RC and DC, MT may play a role in cellular proliferation. However, it seems that MT is either less or is not related to proliferation in OOC and in KOT. Moreover, inflammation does not seem to alter IMT and IK.

Binary system of grading oral epithelial dysplasia: evidence of a bearing to the scores of an immunohistochemical study.

We have recently published two papers concerning the immunohistochemical assessment of hMLH1 and p53, and AgNOR counting in oral leukoplakias (OL). The evaluation has been performed considering each epithelial layer, that is, basal layer’, suprabasal layer’, and all layers’ (1, 2). In those studies, OL have been classified into four groups as presenting no, mild, moderate, or severe dysplasia, as proposed by WHO (3). Carcinoma in situ’ has not been included in our sample. This classification system has been widely used to grade epithelial dysplasia in OL, which in turn is regarded as the most relevant indicator of progression and prognosis, influencing the approach of the patient (4, 5). Nevertheless, many papers discuss the great variability and low reproducibility of grading epithelial dysplasia following that system (4, 6). So, new studies concerning the classification criteria have been performed (7–9). In this field, a binary system was suggested as a more reliable tool, allowing a better management of the patient. According to it, OL showing no ⁄mild ⁄questionable’ dysplasia would be classified as low-risk OL (L-OL), and lesions with moderate ⁄ severe’ dysplasia would be set as high-risk OL (H-OL). This new system would benefit pathologists by reducing classification groups from five to two (4, 6, 9). In a recently published cohort study, Liu et al. (10) suggest that high-risk dysplasia may be regarded as a significant indicator for malignant transformation risk of OL. Based on these discussions, we have decided to perform a new statistical analysis of our data, grouping OL according to the binary system for epithelial dysplasia. We could find quite interesting results (Table 1) and interpretations. Firstly, comparisons between L-OL and H-OL showed statistically significant differences for all hMLH1, p53, and AgNOR indexes, except for AgNOR counting in the basal layer (Table 2). These findings may suggest that the biological processes linked to the impairment of those proteins remain enhancing from L-OL to H-OL. Thus, the use of the binary system would give support to a more reliable clinical approach of removing H-OL. In addition, comparing indexes of hMLH1, p53, and AgNOR in normal oral mucosa and L-OL, we observed statistically significant differences for all p53 indexes and for AgNOR counting considering all layers together (Table 2). This supports the statement that the loss of function of p53 is probably an early event in the oral carcinogenic process. Moreover, we can speculate that these OL may be reasonably named as L-OL, as comparisons among hMLH1 and AgNOR indexes did not reach statistical significance, despite their different median values (Tables 1 and 2). Furthermore, the most noticeable change in the immunoexpression of hMLH1 and AgNOR number would take place in the possible evolution from a L-OL to a H-OL (Table 1). Morphological dysplastic alterations observed in routinely stained slides may be related to molecular changes (3). So, in the light of our new observations, together with previous results, we believe that new research on the binary system for grading epithelial dysplasia in OL has to be encouraged. Maybe this could reduce the variability and enhance the reproducibility of the assessment of epithelial dysplasia, with a better clinical management of the patient. Thus, more discussion on the relevance, applicability, and feasibility of this binary system should be promptly stimulated.

Extra-osseous solitary hard palate neurofibroma

The neurofibroma (NF) is a benign tumor of the peripheral nerve sheath that rarely affects the head and neck. However, among neural lesions, this is the one that most frequently affects this region. The NF can be intra or extra-osseous, alone or multiple (associated with type I neurofibromatosis). The most common extra-osseous mouth NF locations are tongue, oral mucosa and lips. In the literature we found two well-documented cases of solitary extra-osseous NF in the hard palate.