Histopathological and ultrastructural modifications of the articular cartilage in ankylosing spondylarthritis

The present study aims to analyse the articular cartilage in Ankylosing, Spondylarthritis (AS) versus the normal cartilage (18 cases altogether) by histopathological (HE, VG, Pas-Alcian, Gömöri, Safranine O), electronmicroscopic and histoenzymological techniques starting from the finding that the articular exudate in this affection is characterized cytomorphologically by cytosis (6,100/mm3), with polynucleosis (61%) and ragocytosis (25%). Histopathologically, the articular cartilage in AS evinced an alteration of safraninophilic areas and pale zones located in the neighbourhood of synovial lymphoplasmocytic infiltrates, pointing to the depletion of proteoglycans. The cartilage-synovia interference areas are relevant for the invasive nature of the inflammatory infiltrates which erode the cartilage. The histopathological modifications were confirmed ultrastructurally by the existence of some extended areas of revealed collagen, indicative of proteoglycans depletion. Functionally, chondrocytes have a high oxidative potential expressed by the presence of the peroxisomes and the positive reaction of peroxidase (PO), located near the nuclear membrane and the rough endoplasmic reticulum. The corroboration of histopathological, ultrastructural and histoenzymological data shows the alteration of the articular cartilage in AS, expressed morphologically at the level of the chondrocytes and of their synthesis products, collagen and proteoglycans.