HISTOCHEMICAL AND ULTRASTRUCTURAL STUDIES OF ONE CASE OF MYOSITIS OSSIFICANS CIRCUMSCRIPTA

The authors report a study of myositis ossificans circumscripta in a 62 year old man. The histopathology is briefly described; the histochemistry, histoenzymology and ultrastructure of the 3 types of ossification seen in this lesion (membranous, enchondral and osteoblastic ossification), are reported in detail. The reactions for proteins were positive, and especially those for non-sulfated and sulfated acid M.P.S., and for alkaline phosphatase, esterase, dehydrogenase and leucine-aminopeptidase, in the ossifiable connective matrix. The A.T.P.ase activity was much stronger within the mineralized area of the bone. The conditions of the ossification appeared to be normal, but the ultrastructural study revealed an abnormal character of the collagen of the ossifiable mesenchyme. The collagen fiber was short, its period of 280 to 350 Angstroems, indicating a structural modification, which is possibly genetic and familial in origin. Such a factor may account for the pathological ossification. © 1969 Springer-Verlag.