Correlation of Histopathological Findings and Magnetic Resonance Imaging (MRI) in the Spine of Patients with Ankylosing Spondylitis

Heiner Appel; Christoph Loddenkemper; Zarko Grozdanovic; Harald Ebhardt; Marc Dreimann; Axel Hempfing; Harald Stein; Peter Metz-Stavenhagen; Martin Rudwaleit; Joachim Sieper


Arthritis Res Ther. 2006;8(5) 

In This Article

Abstract and Introduction

Ankylosing spondylitis (AS) is a chronic inflammatory disease which affects primarily the sacroiliac joints and the spine. In patients with active disease, magnetic resonance imaging (MRI) of the spine shows areas of bone marrow edema, the histopathological equivalent of which is unknown. In this study we correlate inflammation in the spine of patients with AS as revealed by histological examination with bone marrow edema as detected by MRI. We have compared the histopathological findings of zygapophyseal joints from 8 patients with AS (age: 30 to 64, disease duration 7 to 33 years) undergoing spinal surgery with findings in MRI. For histopathological analysis, we quantified infiltrates of CD3+, CD4+ and CD8+ T cells as well as CD20+ B cells immunohistochemically. Bone marrow edema was evaluated in hematoxylin and eosin stained sections and quantified as the percentage of the bone marrow area involved. All patients with AS showed interstitial mononuclear cell infiltrates and various degrees of bone marrow edema (range from 10% to 60%) in histopathological analysis. However, in only three of eight patients histopathological inflammation and edema in the zygapophyseal joints correlated with bone marrow edema in zygapophyseal joints of the lumbar spine as detected by MRI. Interestingly, two of these patients showed the highest histological score for bone marrow edema (60%). This first study correlating histopathological changes in the spine of patients with AS with findings in MRI scans suggests that a substantial degree of bone marrow inflammation and edema is necessary to be detected by MRI.

The prevalence of ankylosing spondylitis (AS) within Caucasians has been estimated to be between 0.2% and 0.8%.[1,2] About 20% of these patients with AS have bridging syndesmophytes which result in restricted movement of the spine as a consequence of active inflammation in spinal joints and adjacent structures.[3] It has been suggested that the involvement of zygapophyseal joints is important in the restriction of spinal mobility.[3,4,5] This is supported by computed tomography observations, which displayed a significant correlation between changes in the zygapophyseal joints and restriction of spinal mobility.[6,7]

Acute inflammation in the spine associated with AS, as detected by magnetic resonance imaging (MRI), has been described in the intervertebral disc, in the vertebra, enthesis of interspinal ligaments, costovertebral joints and zygapophyseal joints.[8] However, systematic MRI of zygapophyseal joints has not been undertaken so far.

As a consequence, a correlation of histopathological analysis of the spine and inflammation as visualized by MRI has also not previously been done. In the sacroiliac joints of patients with AS, a correlation of MRI findings and histopathological evaluations from needle biopsies out of the same sacroiliac joints was reported, but without description and quantification of histological edema.[9]

We have recently reported the first systematic histological study of zygapophyseal joints in patients with AS.[10] In the present study, we first examined whether inflammation in the spine of patients with AS, as detected by histopathology, can be correlated with bone marrow edema detected by MRI and consequently whether a negative MRI excludes active inflammation of the spine in patients with AS.


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