Morphological and ultrastructural characteristics of extracellular matrix changes in oral squamous cell carcinoma.

ABSTRACT

Background: The biology of oral squamous cell carcinoma (OSCC), including its progression from dysplasia to carcinoma, "field effects", genetic changes in tumor associated mucosa (TAM) and effect of matrix metalloproteinases in breaking down of matrix proteins to facilitate invasion, has been well documented. However, what remains to be done is to extrapolate this knowledge to improve patient care. Aim: The aim of this study was to observe the extracellular matrix (ECM) changes with the routine histochemical stains available to most histopathologists. Materials and Methods: The study includes 72 cases of OSCC in which the tumor and adjacent normal appearing areas were sampled to study the ECM changes with hematoxylin and eosin (H and E) and Verhoeff's-Van Gieson elastic stain (VVG). Results: Basophilic fragmentation of collagen (H and E) and clumped short elastic fibers (VVG) were seen in 12 (16.7%) cases. Of the remaining cases, 18 (25%) had a dense lymphocytic infiltrate and had no demonstrable elastic fibers. Those cases with H and E changes were further studied and compared with normal mucosa for ultrastructural changes. The ultrastructural study demonstrated an increase in oxytalan, elaunin and elastic fibers and decrease in collagen fibers with some transformation changes associated with OSCCs and lymph node metastasis. Conclusion: Changes in transformation of collagen to elastic fibers and also the loss of both the fibers in areas of lymphocytic infiltration possibly indicate degradation of ECM fibers by factors released from the lymphocytes or tumor cells and the limiting effect on the tumor by ECM remodeling.