The production of heterotopic calcification by certain chemical salts.

The subcutaneous injection of small quantities of LaCl3 and CeCl3 was followed by calcification of the dorsal fascia in mice. The calcification reaction was shown by separate positive histochemical tests for calcium ions (the chloranilic acid reaction) and phosphate (the von Kossa reaction). The injection of cadmium chloride and stannous salts caused damage to and a positive von Kossa reaction in the fibres of the panniculus carnosus muscle. The significance and specificity of the histochemical tests was determined by X-ray microprobe analysis of tissues injected with the above salts and other salts known to cause either combined chloranilic acid and von Kossa positive reactions or isolated von Kossa positive reactions in mouse skin. The pathogenesis of the reactions produced by LaCl3, CeCl3 and KMnO4 was studied by applying histochemical tests to tissues recovered at timed intervals after injection. The reactions produced by LaCl3 and CeCl3 were similar and occurred in the dorsal fascia with positive VK reactions occurring first after 18 followed by positive CA reactions after 24 hr. The distribution of these reactions suggested a haematogenous origin for the constituent ions. The injection of KMnO4 in a much higher dose caused damage to the skin and particularly the fibres of the panniculus carnosus muscle. In contrast to the other salts, the calcific reaction occurred in association with these fibres, showing equally positive von Kossa and chloranilic acid reactions from the early stages.