Pathogenesis, Laboratory Studies, and Histopathologic Findings
The pathogenesis of relapsing polychondritis is not known. There is a significant increase in the frequency of human leukocyte antigen (HLA)-DR4 in patients, and the disease is associated negatively with HLA-DR6.[30,44] Oligonucleotide-based genotyping, however, failed to show any predominant HLA-DR4 subtype.[44] HLA-DQ6/8 transgenic mice develop auricular chondritis after immunization with type II collagen.[45] Antibodies to type II collagen, as well as types IX and XI have been described, but they lack sensitivity and specificity.[46,47,48,49] Cell-mediated immunity is important in the pathogenesis of relapsing polychondritis.[50] Levels of macrophage inhibitory factor are significantly higher in patients than in control subjects.[51] Furthermore, one patient has been characterized with T-cell clones specific for a type II collagen epitope.[52*] Rarely, there may be a mechanical insult to cartilage such as ear piercing of the cartilaginous portion, which is temporally correlated with the development of relapsing polychondritis.[53]
Nonspecific markers of an inflammatory state may be present with active relapsing polychondritis. Other serologic tests are of little value, other than to suggest associated diseases. Antineutrophil cytoplasmic antibodies have been found in some patients with relapsing polychondritis.[54] These may be nonspecific or may be associated with overlap syndromes.
Histopathology of involved cartilage specimens in relapsing polychondritis reveals loss of normal cartilage basophilia with hematoxylin-eosin staining and inflammation of the perichondrium with neutrophils, eosinophils, lymphocytes, and plasma cells. Later, cartilage is replaced by granulation tissue and fibrosis.[55] Immunofluorescence studies may show the presence of immunoglobulin and C3 complement deposits along the chondrofibrous junction and in perichondral vessel walls.[56]
Curr Opin Rheumatol. 2004;16(1) © 2004 Lippincott Williams & Wilkins
Cite this: Relapsing Polychondritis - Medscape - Jan 01, 2004.
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