Histological assessment of the early enthesitis lesion in spondyloarthropathy

Abstract

Objectives: To describe the histological changes in acute enthesopathy in early spondyloarthropathies (SpA).

Methods: Clinically evident acute enthesopathy was confirmed by magnetic resonance imaging and ultrasonography in four cases of plantar fasciitis and one case of patellar tendon enthesitis. Ultrasound guided biopsy of insertional points was carried out with a Jamshedi needle. Control tissue was obtained from two subjects undergoing spinal grafting surgery. Standard histochemistry and immunohistochemistry analysis using the avidin-biotin immunoperoxidase complex method employing markers against CD3, CD8, CD34, and CD68 was used to determine cellular infiltrates at the insertion point.

Results: The enthesis architecture was abnormal in the SpA group, with increased vascularity and cellular infiltration compared with normal subjects. The predominant infiltrating cell at the enthesis fibrocartilage was the macrophage, but there was a paucity of lymphocytes at the insertion point.

Conclusion: These preliminary findings have implications for a better understanding of the pathology in early SpA.

Figures

Figure 1

Histology of the plantar fascia employing haematoxylin and eosin (H&E) staining. (A) The sample shows an inflammatory cell infiltrate in the fibrous part of the enthesis with increased vascularity at that site (arrows). The adjacent bone is marked by asterisks. (B) In this sample the osseous part of the enthesis adjacent to the fibrocartilage is disrupted, but the fibrocartilage itself is relatively intact (asterisk). Focal bone defects at sites of fibrocartilage contact with normal bone have been reported in normal insertions (open arrows). There is an inflammatory process in the bone adjacent to the fibrocartilage with increased vascularity (arrows) and proliferation of stromal tissue.

Figure 2

Immunohistochemistry using the ABC method showing the presence of macrophages in the enthesis in fibrous tissue at enthesis (open arrows) (A) and in the entheseal fibrocartilage (B) with prominent CD68 positive staining. There is no CD3 (C) or CD8 (D) positive lymphocytic infiltration at these sites. The increased vascularity within the enthesis is demonstrated by CD34 positivity (open arrows) (E).