Relapsing polychondritis: an ultrastructural study

Ear cartilage from a typical case of relapsing polychondritis was examined with the electron microscope. A large number of dense granules and vesicles, which were compatible with matrix vesicles or lysosomes, surrounded the affected chondrocytes. In less severely damaged chondrocytes, these granules and vesicles appeared to be formed by pinching off of the cytoplasmic processes or by budding from the processes. Calcification of the granules was minimal. In severely damaged chondrocytes, an admixture of these granules and cytoplasmic organelles occurred. It is speculated that many of these dense granules are lysosomal in nature and that they may produce inflammation and reduce the proteoglycan content of cartilage.