Quantitative Assessment of Collagen Architecture to Determine Role of Tumor Stroma During Vestibular Schwannoma Progression.

Objective: The primary objective was to characterize the abundance and architecture of collagen in the extracellular matrix in vestibular schwannoma (VS). The secondary objective was to investigate the association between collagen architecture and tumor size.

Study design: Retrospective cohort study.

Setting: Academic referral center.

Methods: Tumor samples were obtained from patients with sporadic VS undergoing microsurgical resection. Histological analyses were performed including picrosirius red (PSR) staining under polarized light. Collagen architecture was quantified using an automated fiber detection software. Second Harmonic Generation (SHG) microscopy and immunofluorescence (IF) were utilized to characterize collagen architecture.

Results: Eleven tumor specimens were included (mean tumor diameter = 2.80 cm, range 1.5-4.0 cm), and were divided into large (mean diameter = 3.5 ± 0.4 cm) and small (mean tumor diameter = 2.0 ± 0.4 cm) cohorts based on size. The large VS cohort showed significantly higher collagen density (27.65% vs 12.73%, P = .0043), with more thick fibers (mature Type I, 24.54% vs 12.97%, P = .0022) and thin fibers (immature Type I or mature Type III, 23.55% vs 12.27%, P = .026). Tumor volume correlated with greater degree of collagen fiber disorganization (P = .0413, r² = 0.298). Specifically, collagen type I intensity was significantly higher in large VS compared to small tumors (P < .001) and peripheral nerve (P = .028).

Conclusion: Larger VS exhibit increased collagen abundance in the tumor stroma, and a more disorganized collagen architecture compared to smaller VS and normal peripheral nerve tissue. This finding indicates that collagen organization may play a significant role in extracellular matrix remodeling and the progression of VS.