In 11 patients with eczema localized mainly on the legs, 11 cases of sensitization were observed to brilliant green. In these cases, a simultaneous sensitivity to gentian violet—crystal violet—was found in eight and to malachite green in six patients. Patch tests with various triphenylmethane (TPM) dyes have shown the possibility of crosssensitization between crystal violet (contained in gentian violet), brilliant green, and malachite green. The probable determinant groups of sensitization are —N(CH3)2 or —N(C2H5)2 in the para position of the benzene ring structure. Cross-re actions are limited only to substances with aminogroups substituted with at least two alkyls. The test reactions to TPM and pararosaniline were in all cases negative.
Bielicky T, Novák M. Contact-Group Sensitization to Triphenylmethane DyesGentian Violet, Brilliant Green, and Malachite Green. Arch Dermatol. 1969;100(5):540-543. doi:10.1001/archderm.1969.01610290024005