Related Experiment Videos
Reassessment of the PAS patterns in uveal melanoma
A J Foss1, R A Alexander, J L Hungerford
1Department of Clinical Science, Institute of Ophthalmology, London.
Background:
Previous work has highlighted the prognostic importance of patterns of periodic acid Schiff (PAS) staining (the Folberg patterns) in uveal melanoma. These patterns have been ascribed to blood vessels but the patterns are different from those seen with other staining techniques for blood vessels. It has recently been shown that microvessel density is the dominant prognostic factor in uveal melanoma. This study reinvestigates the nature and significance of the PAS patterns.
Methods:
The PAS patterns were compared with the patterns seen with conventional connective tissue stains and with the patterns seen in sections stained for the presence of blood vessels (by immunohistochemistry for factor VIII related antigen). The PAS patterns were determined on a panel of 117 cases of uveal melanoma. The prognostic significance of each of these patterns was determined and, as more than one pattern can exist in a tumour, principal components analysis was performed to determine the number of underlying factors.
Results:
Comparison of the PAS patterns with other stains demonstrates that they are based on connective tissue including fibrovascular tissue. Five of the nine PAS patterns carried prognostic significance on univariate analysis. Principal components analysis suggested that these patterns represented three underlying factors, which were tentatively identified as representing disordered growth (factor 1), emergence of rapidly growing subclones (factor 2), and section orientation (factor 3).
Conclusions:
The PAS patterns are based on fibrovascular tissue and can be ascribed to three underlying factors. The first two of these factors carried prognostic significance and the first (disordered growth) retained independent prognostic significance in a multivariate Cox model which included microvessel density and tumour size.
Insights
Periodic acid Schiff (PAS) staining patterns in uveal melanoma are linked to fibrovascular tissue. Disordered growth patterns show independent prognostic significance, aiding in understanding tumor behavior.
Area of Science:
- Ophthalmology
- Oncology
- Pathology
Background:
- Periodic acid Schiff (PAS) staining patterns, known as Folberg patterns, have prognostic importance in uveal melanoma.
- Previous assumptions linked these patterns to blood vessels, but observed patterns differ from standard vascular stains.
- Recent research identifies microvessel density as a key prognostic factor in uveal melanoma.
Purpose of the Study:
- To investigate the nature and prognostic significance of PAS staining patterns in uveal melanoma.
- To clarify the relationship between PAS patterns and vascular and connective tissue components.
- To determine the underlying factors contributing to observed PAS patterns and their prognostic value.
Main Methods:
- Compared PAS patterns with conventional connective tissue stains and Factor VIII-related antigen immunohistochemistry for blood vessels.
- Analyzed PAS patterns in a cohort of 117 uveal melanoma cases.
- Utilized principal components analysis to identify underlying factors from multiple co-existing PAS patterns.
Main Results:
- PAS patterns are derived from fibrovascular tissue, not solely blood vessels.
- Five of nine identified PAS patterns demonstrated prognostic significance via univariate analysis.
- Principal components analysis revealed three underlying factors: disordered growth, emerging subclones, and section orientation.
Conclusions:
- PAS patterns in uveal melanoma are based on fibrovascular tissue and can be attributed to three underlying factors.
- Two factors, disordered growth and emerging subclones, exhibited prognostic significance.
- Disordered growth, the first factor, maintained independent prognostic significance in a multivariate model including microvessel density and tumor size.