The ultrastructure of topical cutaneous calcinosis

Abstract

Mineralized plaques, which develop at the site of repeated subcutaneous injections of 100 mug KMnO4/0.2 H2O in rats, were investigated by electron microscopy. The newly formed, delineated, white plaque tissue at the injection site consisted of numerous, mostly unaltered fibroblasts and collagen fibers, without participation of inflammatory cells. Some signs of cell injury were found in the center of the lesions. Numerous, irregularly distributed, small, mineralized foci were seen near the fibroblasts. These were formed by aggregation of small needle-like units (50 A in diameter and 0.05-2.0 mum long). These needle-shaped units were found either in vesicular, cell derived structures, considered to be shed cell fragments, or on collagen fibers. Intramitochondrial deposits of such needle like units were seen frequently. Fusion of smaller mineralized foci to larger plaques occured and then needle-shaped units were seen at the periphery of the electron-dense lesions. Hypotheses concerning the mechanism of experimental cutaneous calcinosis (soft tissue mineralization) are discussed and related to the findings of this study. Probable intracellular crystal deposition and mineralization in cell-derived structures were shown for the first time in topical cutaneous calcinosis.

Biological Calcification

“…In topical calciphylaxis, calcification was again first detected in mitochondria, followed soon after by extracellular calcification occurring in matrix vesicles, then around and between collagen fibrils, and finally within collagen fibrils. Crystals are reported to develop in connection with collagen fibrils and with structures derived from the cells (Placková 1975), and to be located around and between collagen fibrils Walzer et al 1980;Vandeputte et al 1990), in association with the interfibrillary ground substance (Seifert and v.Hentig 1967). Probably as a result of the denaturing effect of permanganate, other initial dermal changes in calcergy have, however, been described, including loosening of fibrous tissue, swelling of fibroblasts, partial lysis of fibrils, proliferation of fibroblasts, increase in acid proteoglycans and alkaline phosphatase activity (Seifert and v.Hentig 1967;Seifert 1970); these are followed by the formation of crystals.…”

Non-Specific Induction of Mineralization of Incisor Pulp in the Rat

“…(1)(2)(3)(4)(5) Similar mineralized lesions were *induced in rabbits(6) and rats (7,8) after a single injection of potassium permanganate, into the incisal end of the pulp of the continually growing incisors. This phenomenon, called "simple calcergy" or "topical calcinosis", which stimulates the formation of mineralized tissue, may gain importance in pulp capping or in the healing of periapical lesions.…”

Calcifying Matrices: Pathological Calcifications

“…In topical calcergy, mitochondrial granules and matrix vesicles were the early sites of calcification (Walzer et al 1980). Crystals are reported to develop in connection with collagen fibrils and with structures derived from the cells (Placková 1975), and to be located around and between collagen fibrils (Boivin 1975;Boivin et al 1987;Walzer et al 1980;Vandeputte et al 1990), in association with the interfibrillary ground substance (Seifert and v.Hentig 1967). Crystals are reported to develop in connection with collagen fibrils and with structures derived from the cells (Placková 1975), and to be located around and between collagen fibrils (Boivin 1975;Boivin et al 1987;Walzer et al 1980;Vandeputte et al 1990), in association with the interfibrillary ground substance (Seifert and v.Hentig 1967).…”