[Amyloid in articular cartilage--a new type of amyloid?]

Hip and knee joints from 48 randomly selected autopsies have been investigated for amyloid deposits by means of conventional histology and immunohistology. 45 of 48 hip joints (93.75%) and 28 of 32 knee joints (87.5%) contained amyloid deposits. Amyloid has been found in a thin layer along the surface as well as infissures of the cartilage and around chondrocytes with increasing intensity towards the articular surface. Amyloid characteristically showed apple green birefringence in polarized light after staining with alkaline Congo red and pretreatment with potassium permanganate did not change intensity of reaction in most cases. None of the usual constituents of amyloid could be demonstrated by immunohistological methods. P-component (when present) kept the distribution of the amyloid material. It is possible that articular cartilage amyloid represents a new class of amyloid but its identity is to be proved by chemical analysis.