Histochemical Analysis of Collagen Reorganization at the Tumor-Stromal Interface in Oral Squamous Cell Carcinoma- A Polarizing Microscopic Study

Research Article

Austin J Dent. 2016; 3(2): 1034.

Histochemical Analysis of Collagen Reorganization at the Tumor-Stromal Interface in Oral Squamous Cell Carcinoma- A Polarizing Microscopic Study

Alrani D, Niranjan KC*, Acharya S and Hallikeri K

Department of oral Pathology, SDM College of Dental Science and Hospital, India

*Corresponding author: Niranjan KC, Department of Oral Pathology, SDM College of Dental Science and Hospital, Dharwad, Karnataka, India

Received: March 23, 2016; Accepted: May 24, 2016; Published: May 26, 2016

Abstract

Stromal changes are the key factors for provision of nutrition and growth to any tumor and also they act as a barrier for spread of the tumor. There are limited histochemical studies in the literature on methods to detect, quantify and analyze the collagen in the invasive tumor front (ITF) of oral squamous cell carcinoma (OSCC).

Aim: 1) To analyze the nature of collagen (thickness, hue, density, birefringence) with respect to cohesive and discohesive tumor front of oral squamous cell carcinoma. 2) To correlate the nature of collagen at the different grades (Broder’s and Bryne’s grading system) of oral squamous cell carcinoma. 3) Clinicopathological correlation with the nature of collagen at the invasive front of oral squamous cell carcinoma.

Materials and Methods: Tissue sections of 30 OSCC cases with ITF were stained with hematoxylin and picrosirius red stains for evaluation of the nature of collagen under polarizing microscope.

Results: Tumor with cohesive front will have thick collagen fiber which is predominantly organized red- yellow in color, well packed and shows strong birefringence (p< 0.005). A gradual change in the nature of collagen fiber was observed in the discohesive tumor front where the collagen fiber were thin disorganized, yellow-orange to green-yellow in color loosely packed with weak birefringence (p< 0.005).

Conclusion: Cohesive tumor front with organized collagen fibers resist the tumor against invasion and metastasis, preventing it to increase in size and thus associated with initial stage of tumor (I&II) whereas in discohesive tumor front the fibers may enhance the movement of tumor cells towards invasion and metastasis.

Keywords: Collagen; Picrosirius Red (PSR); Oral Squamous Cell Carcinoma (OSCC); Invasive Tumor Front (ITF); Cohesive tumor front; Discohesive tumor front

Introduction

OSCC is composed of two discrete components, the malignant epithelial cells and the stroma in which they are dispersed [1]. One of the major aspects of tumor cell invasion and metastasis is the interaction between cancer cells and extracellular matrix component [2]. The stroma is composed of ground substance composed of proteoglycans, glycoproteins and water, the fibrous component including interstitial collagen and elastic fibers [3]. Extracellular matrix components are the key factors for nutrition and growth to any tumor and also they act as barrier for spread of the tumor [4]. Alteration in ECM may play a role in recurrence and in facilitation the invasion of tumor cells.

Collagen which constitutes 34% of the total extracellular matrix (ECM) proteins forms the integral part of connective tissue stroma and plays a vital role in maintaining structural integrity and in determining tissue function. The collagenous tissue in the stroma gives strength to the tumor by giving a skeleton to the tumor. Increase in collagen content of the extracellular matrix increases the mechanical stiffness and transport resistance of the tumors [3]. A recent study by Li, et al. in 2013 mentions that collagen fiber plays an important role in ECM destruction and remodeling [2], so the study of interstitial collagen has been the mainstay of investigative histological procedures in understanding the pathogenesis of the lesion.

Collagen has natural birefringence which is attributed to the arrangement of its fibers which is enhanced by special stains like van gieson, masson’s trichrome and picrosirius red. Picrosirius red stain is considered a highly specific and selective stain for collagen fibers due to its ability in differentiating between different types of collagen fibers in various pathological conditions.

There are limited histochemical studies in the literature on methods to detect, quantify and analyze the collagen in the tumor invasive front of oral squamous cell carcinoma (OSCC).

Aims and objectives

1. To analyze the nature of collagen (thickness, hue, density, birefringence) with respect to cohesive and discohesive tumor front of oral squamous cell carcinoma.

2. To correlate the nature of collagen at the different grades (Broder’s and Bryne’s grading system) of oral squamous cell carcinoma.

3. Clinicopathological correlation with the nature of collagen at the invasive front of oral squamous cell carcinoma.

Materials and Methods

Twenty nine histologically diagnosed cases of OSCC and two controls of normal mucosa were retrieved from the archives of Department of Oral Pathology, S.D.M College of Dental Sciences and Hospital, Dharwad. All the sections were subjected to haematoxylin and eosin and also picrosirius red (PSR) staining, Sirius Red F3B (C.I.35780). All the patients were subjected to radical surgery, accompanied by removal of lymph nodes conducted in S.D.M College of Dental Sciences and Hospital from year 2009 to 2015.

Majority of the OSCC cases showed discohesive tumor front 19 (63%) which is represented by high degree of tumor cell dissociation followed by cohesive tumor front 11 (37%) (Table 1), clinicopathological features of Oral Squamous cell carcinoma patients.