Evaluation of stromal myofibroblasts expression in keratocystic odontogenic tumor and orthokeratinized odontogenic cysts: A comparative study

Myofibroblasts and increased angiogenesis contribute to periapical cystic injury containment and repair

Background

Myofibroblasts (MF) and angiogenesis are important factors in the development and expansion of cystic lesions, where these cells secrete growth factors and proteases, stimulating angiogenesis, matrix deposition and cell migration, affecting the growth of these periapicopathies. The present study aimed to evaluate the immunohistochemical expression of CD34 and α-SMA in radicular cysts (RC) and residual radicular cysts (RRC), with the purpose of contributing to a better understanding of the expansion and progression of these periapical lesions.

Material and Methods

The present study os a descriptive, quantitative and comparative analysis of positive CD34 and α-SMA immunohistochemical expressions in 30 RC and 30 RRC specimens. α-SMA expression was evaluated in the fibrous capsule of the lesions, at 100x magnification below the epithelial lining. A total of 10 higher immunostaining fields were selected and subsequently, positive cells were quantified at 400x magnification, averaged per field. Regarding the angiogenic index, immuno-labeled microvessel counts for the anti-CD34 antibody were performed in 10 fields at 200x magnification.

Results

Statistically significant differences regarding α-SMA immunostaining were observed (p = 0.035), as well as a correlation between α-SMA versus CD34 (p = 0.004) in RRC. However, the angiogenic index obtained by immunostaining for CD34 indicated no statistical difference between lesions. Intense inflammatory infiltrates were predominant in RC, while mild and moderate degrees were more commonly observed in RRC (p <0.001). Intense inflammatory infiltrates were also more often noted in larger RRC (p = 0.041). Inflammatory infiltrates showed no significant correlation with α-SMA and CD34 immunostaining.

Conclusions

The results indicate that the significant correlation found between the presence of MF and the angiogenic index are related to the repair process in RRC.

Key words:Myofibroblasts, angiogenesis, inflammatory odontogenic cysts.

Myofibroblasts and mast cells: influences on biological behavior of odontogenic lesions

Odontogenic lesions differ in their rate of recurrence and aggressiveness. This study aimed to evaluate the presence of myofibroblasts and mast cells in odontogenic lesions. Sample consisted of 20 cases each of dentigerous cysts, odontogenic keratocysts, and solid ameloblastomas. Histologic sections were submitted to immunohistochemistry using anti-α-smooth muscle actin and anti-tryptase antibodies. Myofibroblasts and mast cells were counted at ×400 magnification in 5 and 10 fields, respectively. Myofibroblasts were more frequent in ameloblastomas (24.41), followed by odontogenic keratocysts (16.21) and dentigerous cysts (11.85; P=.002). Granulated and degranulated mast cells were more frequent in dentigerous cysts (7.88 and 8.96, respectively), followed by odontogenic keratocysts (6.53 and 7.08) and ameloblastomas (5.21 and 1.88). The difference was only significant for degranulated mast cells (P<.05). Analysis of the correlation between myofibroblasts and mast cells (granulated and degranulated) revealed a moderate positive correlation only in ameloblastomas (R=0.621, P=.003). Probably, myofibroblasts are related to the biological behavior of the odontogenic lesions studied, particularly their aggressiveness. On the other hand, mast cells seem to be associated with inflammatory processes, which are more frequent in cystic lesions than in benign neoplasms. In addition, mast cells may induce the differentiation of fibroblasts into myofibroblasts, thus increasing the number of the latter.

Multiple orthokeratinized odontogenic cysts: a case report

The purpose of this report is to document the clinical, radiographic, pathological and molecular findings of the first case of multiple orthokeratinized odontogenic cysts (OOCs). Multiple odontogenic keratocysts are one of the major features of nevoid basal cell carcinoma syndrome (NBCCS), and loss of heterozygosity in the PTCH gene, the culprit gene for NBCCS, has recently been found in sporadic OOC cases. Therefore, in this presenting case, we also investigated the possibility that this patient might also have NBCCS, by comparing the available clinical information and the molecular findings of this case to the diagnostic criteria for NBCCS (as proposed by the First International Colloquium on NBCCS in 2011). However, this patient with multiple OOCs showed no evidence of having NBCCS. This conclusion supports the findings from previous case series based on sporadic cases that OOC does not appear to be associated with NBCCS.