Assessment of collagen birefringence in different grades of oral squamous cell carcinoma using Picrosirius red - polarizing microscopy and comparison with Picrosirius red - Fast green stain.

内容摘要

Oral squamous cell carcinoma (OSCC) is among the most common cancers globally, with significant prevalence in India. While OSCC is primarily an epithelial malignancy, its interaction with the surrounding stroma influences tumour progression. The stromal response may facilitate invasion via collagen degradation or inhibit it through desmoplasia. To comparatively evaluate stromal collagen alterations in different histological grades of OSCC using Picrosirius Red and PSR-Fast Green staining with emphasis on staining characteristics, birefringence patterns, and morphometric analysis. A total of 60 archival OSCC specimens comprising well-differentiated (n = 20), moderately differentiated (n = 20), and poorly differentiated (n = 20) cases, along with 10 normal oral mucosa controls, were stained with PSR, PSR-Fast Green, and haematoxylin-eosin. Collagen fibres were evaluated under polarized light (PSR) and bright-field microscopy (PSR-Fast Green). Morphometric analysis-including fibre thickness, arrangement, and birefringence intensity-was performed using ImageJ software. Well-differentiated OSCC displayed thick, parallel, dense collagen fibres with strong orange-red birefringence. Moderately differentiated OSCC exhibited intermediate features with mixed birefringence. Poorly differentiated OSCC showed thin, disorganized, loosely arranged collagen fibres with weak green birefringence under polarized light. PSR-Fast Green staining offered comparable results with enhanced bright-field contrast. Collagen architecture and birefringence diminish with increasing OSCC grade, indicating progressive stromal degradation that likely facilitates tumour invasion. Evaluating stromal collagen using PSR and PSR-Fast Green may provide diagnostic and prognostic value in OSCC.