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Hyalinization is a process of conversion of stromal connective tissue into a homogeneous, acellular translucent material. Nevertheless, hyalinization could provide insights into the biologic behaviour and prognosis of pathological lesions. Few studies with limited sample size have intended to assess the correlation of hyalinization and biologic behaviour in oral lesions. The current review aims to comprehensively appraise the mechanism of hyalinization in pathological oral hyalinizing lesions (OHL) and its clinical implications with emphasis on differential stains employed. An electronic search was performed in the PubMed database (from year 2000–2020) using the keywords "special stains in oral hyalinizing lesions", "significance of hyalinization in oral lesions" and "hyalinization and biologic behaviour". Original research articles analyzing the effect of hyalinization on biologic characteristics of the lesion were evaluated in this review. Narrative review articles that provided insights into the mechanism of hyalinization and maturity of collagen fibers were also considered for analysis. The presence of hyalinization does seem to have a significant effect on the biologic behaviour of pathological lesions. There is substantial scope to further investigate the process of hyalinization on larger samples and its correlation with the aggressive behaviour of OHLs. Special stains and advanced investigations such as immunohistochemistry for stromal markers would define the nature of hyalinized material and validate the correlation. The prediction of the biologic behaviour of a lesion established through assessment of hyalinization would prevent unwanted over or under treatment leading to a better prognosis. [ABSTRACT FROM AUTHOR]

Background The present study was aimed to evaluate and analyze orientation and birefringence pattern of collagen fibers histopathologically in different grades of OSMF using the special stain (Picrosirius red) under polarizing microscope and relate these factors with the severity of OSMF. Materials and Method 45 confirmed cases of OSMF were taken from the archives. The selection of clinical cases was done according to classification by J.N Khanna and Andrade (1999). These cases were correlated histopathologically as per the criteria given by Pindborg J.J and Sirsat S.M (1966). The sections were stained with H & E and Picrosirius red stains and assessment was done accordingly. 10 cases of normal mucosa were taken as control. Results In clinical grade I, 60% of the cases showed histopathological grade II, while 53.4% cases in clinical grade II correlated with histopathological grade III and 33.4% of clinical grade III cases showed histopathological grade IV. Upon application of Fisher’s exact test a significant P value <.01 was obtained suggesting no statistical significant correlation between these two parameters. However, the orientation pattern revealed a parallel orientation as OSMF advanced. Also as the severity of the disease increased, there was a gradual shift from green- greenish yellow colour of the fibres and a shift to orange red-red colour. Conclusion Upon correlation of clinical grades with histopathological grades, no statistically significant difference was found. Birefringence pattern of collagen revealed similar findings as other studies in case of clinical grades but histopathological grades showed a contrast finding. [ABSTRACT FROM AUTHOR]

Collagen plays essential roles in remodeling uterine tissue during decidualization, implantation, pregnancy and involution. To understand whether the progestational agent medroxyprogesterone acetate (MPA) can modify the organization and deposit of collagen in the uteri of normal bitches (Canis Tlupus familiaris), we assessed uterine tissues by histochemistry. Uteri were grouped as: nulliparous (n=11), multiparous (n=11) and treated with MPA (n=11; nulliparous with two treatments; 5mg/kg; i.m.). The amount, location and birefringence of interstitial collagen types I and III in the fold and base of the endometrial stroma and the myometrial muscular layers were studied on sections stained with Picro-sirius Red by polarized light microscopy and evaluated by ANOVA. No differences were observed in the endometrium. In the myometrium, differences were observed in collagen type I between MPA-treated and nulliparous uteri vs. multiparous (p<0.05), and differences in collagen type III between nulliparous and multiparous uteri vs. MPA-treated (p=0.0001). In conclusion, two doses of MPA had no significant effect on the investigated collagens in the extracellular matrix. [ABSTRACT FROM AUTHOR]

Introduction Collagen, the most abundant protein in the body, is not only responsible for maintaining the functional integrity of tissues but is also thought to play an important role in pathogenesis and invasion in oral squamous cell carcinoma (OSCC). Aim The study aimed to assess the thickness as well as maturation of collagen fibres in erosive and infiltrative patterns of OSCC in order to determine the possible role of stromal components (collagen) in bone invasion. Materials and methods Histometric analysis was performed on 1350 collagen fibres in 14 cases of OSCC exhibiting either an erosive or an infiltrative pattern of mandibular invasion using polarizing microscope under oil immersion. Two consecutive sections of 5 μm thickness from each sample were taken and stained with haematoxylin and eosin (H&E) and picrosirius red stain, respectively, to enable visualization and counting of thickness of fibres. Results A significantly higher percentage of thick fibres and a greater amount of green/no colour birefringence were observed in cases of OSCC that exhibited an infiltrative pattern of bone invasion. Conclusion The stromal component plays an important role in the biological behaviour of a tumour. It is probable that in OSCC the infiltrative pattern of bone invasion induces increased production of loosely packed procollagens, intermediates, or pathological collagen which further aids in the invasion of the tumour into the surrounding bone, worsening the prognosis. [ABSTRACT FROM AUTHOR]

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Abstract: Epithelial–mesenchymal interactions are thought to play an important role in the pathogenesis of odontogenic lesions. Keratocystic odontogenic tumour (KCOT) is a benign cystic neoplasm with a characteristic parakeratinized epithelial lining, which differs histologically and behaviourally from the so-called orthokeratinized odontogenic cyst (OOC). The purpose of this study was to investigate the differences in collagen fibres within the fibrous tissue walls of KCOT and OOC. Formalin-fixed paraffin-embedded tissue samples from 15 cases of KCOT and 15 cases of OOC were collected. Paraffin sections were stained with picrosirius red and observed under a standard light microscope using optical polarization. Unicystic ameloblastoma (UA, 15 cases) and subcutaneous epidermoid cysts (EC, 15 cases) were included in the study for comparative purposes. Significant difference was detected between the polarization colours in the fibrous tissue walls of KCOT and OOC (P <0.05), whilst no significant differences were found between KCOT and UA and between OOC and EC (P >0.05). The stromal collagen fibres of KCOT were different from those of OOC, but similar to those of UA, which suggests that the stroma of KOCT may play an important role in determining the neoplastic behaviour of the lesion through epithelial–mesenchymal interaction. [Copyright &y& Elsevier]