Density of PAS positive patterns in uveal melanoma: Correlation with vasculogenic mimicry, gene expression class, BAP-1 expression, macrophage infiltration, and risk for metastasis

Mol Vis. 2019 Sep 21;25:502-516. eCollection 2019.


Purpose: Periodic acid-Schiff (PAS) positive patterns of vasculogenic mimicry (VM) have been associated with poor prognosis in uveal melanoma (UM). We examined these patterns with digital image analysis and transmission electron microscopy, and correlated them with BAP-1 expression, gene expression class, macrophage infiltration, and metastatic disease in full tumor cross-sections and intratumor regions.

Methods: Thirty-two enucleated eyes with UM were stained immunohistochemically (BAP-1, laminin, CD31, and CD68) and with PAS without hematoxylin counterstain. Retrospective data on gene expression class and patient survival were retrieved. Tumor sections were digitally scanned and analyzed with the QuPath Bioimage analysis software, and imaged with transmission electron microscopy.

Results: The mean area proportion covered by CD31, laminin, and PAS positive patterns in tumor cross-sections was 0.9% (SD 0.6), 3.0% (SD 1.9), and 8.4% (SD 5.9), respectively. PAS density was statistically significantly greater in tumors with gene expression class 2 (p=0.02). The cumulative 5-year metastasis-free survival decreased for each quartile of increased PAS density (1.0, 0.75, 0.40, and 0.17, p=0.004). Forty percent of the tumors had heterogeneous BAP-1 expression. Intratumor regions with low BAP-1 expression were more likely to harbor VM (p<0.0001), and had statistically significantly greater PAS density (p<0.0001) and number of CD68 positive cells (p=0.01).

Conclusions: PAS positive patterns in UM are composed of a mixture of blood vessels and extracellular matrix (ECM), including VM. Increased density of PAS positive patterns correlated with gene expression class and metastasis, and colocated to tumor regions with macrophage infiltration and low BAP-1 expression.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Choroid / blood supply
  • Choroid / pathology
  • Choroid / ultrastructure
  • Disease-Free Survival
  • Eye Enucleation
  • Female
  • Gene Expression Regulation, Neoplastic*
  • Humans
  • Kaplan-Meier Estimate
  • Logistic Models
  • Macrophages / metabolism
  • Macrophages / pathology*
  • Male
  • Melanoma / blood supply*
  • Melanoma / genetics*
  • Melanoma / pathology
  • Melanoma / ultrastructure
  • Middle Aged
  • Neoplasm Metastasis
  • Neovascularization, Pathologic / genetics*
  • Neovascularization, Pathologic / pathology
  • Pattern Recognition, Automated
  • Periodic Acid-Schiff Reaction*
  • Tumor Suppressor Proteins / genetics*
  • Tumor Suppressor Proteins / metabolism
  • Ubiquitin Thiolesterase / genetics*
  • Ubiquitin Thiolesterase / metabolism
  • Uveal Neoplasms / blood supply*
  • Uveal Neoplasms / genetics*
  • Uveal Neoplasms / pathology
  • Uveal Neoplasms / ultrastructure
  • Young Adult


  • BAP1 protein, human
  • Tumor Suppressor Proteins
  • Ubiquitin Thiolesterase

Supplementary concepts

  • Uveal melanoma