The immunohistological distribution of
collagen types I, II, III, and VI in five cases of extraskeletal
chondroma was examined and compared with that in six cases of
enchondroma. In addition, the composition of crystals deposited in three cases of extraskeletal
chondroma were biophysically analyzed with special attention to the relationship between the
collagen types of the matrix and the crystal deposition. In extraskeletal
chondroma, immunoreactivity of
type II collagen in the extracellular matrix and
type VI collagen in the pericellular area, which were strongly and diffusely recognized in the normal hyaline cartilage and
enchondroma, was diminished. Instead, additional types of
collagen, types I and III, were demonstrated in the matrix. Electron roentgenographic microanalysis and infrared light spectroscopic analysis revealed that
calcium pyrophosphate dihydrate (CPPD) was included in the crystals of extraskeletal
chondroma. CPPD crystals were observed in/around
collagen types I and III. The possible relationship between the difference of
collagen composition in the matrix and the CPPD crystal deposition is discussed.