Vital Staining with Alizarin in Clinical Malignant Conditions of Bone

Madder, or Rubia tinctorum, is a plant which has been known for centuries. A marked staining of the growing ends of all bones in young animals was obtained with madder. The teeth were stained at their roots. In 1736 Belchier (1) noted that bones of cooked pork had a reddish tinge, assuming, correctly, that madder was the factor that reddened the bones of the pigs. Duhamel (4), in 1739, introduced the coloring of growing bone with madder in ossification studies. Alizarin was recognized as the principal staining ingredient of the plant in 1826, by Robiquet and Colin (11). In 1869 alizarin was synthesized. Gottlieb (6), in 1914, expressed the belief that alizarin has a specific chemical affinity for calcium. According to Cameron (1930) the tinctorial effect in the hard tissues is due to the property of alizarin to form a dye-lake with calcium, for which it is nearly a specific stain. Schour et al. (12) (1941) state that alizarin has a selective staining effect upon the calcifying or calcioreceptive zone of the collagenous matrix where calcium salts are being deposited. Vital staining with alizarin was applied in experimental studies of pathological calcifications, such as fractures and callus formation, by Brooks (2) in 1917, and to calcareous deposits in the aorta in 1932, by Ham (5). Cameron's (3) extensive investigations included staining of artificial deposits of calcium, fractures, calcium “casts” in the kidney, regenerating bone and calcified tissue, pathological calcification in hypervitaminosis, and calcification of the kidney following ligation of the renal vessels. It was our purpose to study the behavior of alizarin as a staining material in malignant bone conditions in vivo, and to that end injections of alizarin were given to patients with metastatic bone lesions. We considered the possibility that even in the osteolytic type of metastasis there may exist new bone formation, which possibly could be identified by this vital-staining method. Our assumption of new bone formation in malignant osteolytic bone metastases seemed to be substantiated by the staining of the metastatic areas with the dye. Even minute metastatic deposits measuring as little as 1 mm., not demonstrable by plain radiography, could be detected by alizarin vital staining. It was obvious, therefore, that it would be worthwhile looking for a chemical iodine-alizarin compound as a radiopaque substance and a radioactive iodine-alizarin compound for eventual diagnostic or therapeutic purposes. Chemical preparations are being investigated; an account of them will be given in a separate paper. No clinical or experimental bone studies with alizarin in malignant conditions in man have so far been described in the literature. Chemistry: The general formula of alizarin is 1,2-dihydroxyanthraquinone. It exists in madder as a glucoside, together with purpurin and purpurin 3-carboxylic acid.