Figure 2.

Positive correlation of bone marrow edema in histopathological assessment and magnetic resonance imaging. (a) Magnetic resonance imaging (T2 sequence) of a zygapophyseal joint with bone marrow edema (cyan arrow) (asterisk, vertebral body; open square, epidural space; plus signs, superior and inferior articular processes of the zygapophyseal joint; hash sign, processus spinosus). (b) Hematoxylin and eosin staining, revealing dense infiltrations of mononuclear cells (yellow arrow) and interstitial bone marrow edema (red arrow). (c) Immunohistochemical analysis of CD3⁺ T cells, revealing mononuclear cell aggregates in the same zygapophyseal joint (yellow arrow).