# A significant difference of synovial mast cells in synovium from rotator cuff arthropathy compared to rotator cuff tears: A histological pilot study

## TL;DR

This study found more mast cells in synovial tissue from patients with rotator cuff arthropathy compared to controls, suggesting a possible role in osteoarthritis.

## Contribution

The study is the first to report a significant difference in synovial mast cell distribution in rotator cuff arthropathy compared to rotator cuff tears.

## Key findings

- OA samples had significantly more mast cells and higher synovitis scores than controls.
- Mast cell numbers correlated with patient-reported pain (VAS score).
- Vessel counts and area were also higher in OA patients.

## Abstract

Aim of the present study was to compare the presence of Mast Cells (MCs) in synovial samples from gleno-humeral osteoarthritis (OA) and from control group.

Synovial tissue samples were obtained during arthroplasty from 23 patients with gleno-humeral OA due to rotator cuff arthropathy (RCA) and from 20 patients without OA, constituting OA group and control group respectively. Before surgery self-reported pain was assessed using VAS score and OSS was used to value functional ability. Shoulder radiograph (Antero-posterior, Y-view and Grashey views) was evaluated by musculoskeletal radiologist and graded according to modified Samilson-Prieto classification.

Synovial tissue, obtained during arthroplasty and arthroscopic procedure, was prepared to immunohistochemical analysis with anti-CD31 and anti-CD117 antibodies, to detect respectively endothelial cells and MCs at 40x magnification. Synovitis scores have been assessed. Under the control of the image processing system the distribution and the total number of vessels and MCs were determined.

The numbers of MCs and the area fraction (20x magnification) occupied by them were significantly higher in OA samples than in control tissue. The synovitis score was higher in OA patients with a positive correlation. Vessels number and area fraction were higher in OA patients than in controls. Analysis of MC number in relation to clinical data indicated positive correlation with the VAS score.

The distribution of MCs on synovium significantly differ between OA and control groups. Despite the design of the study could not conclude the cause-effect relationship, the presence of MCs might have role in OA pathogenesis.

Histological study.