Allergic and irritant contact dermatitis compared in the treatment of alopecia totalis and universalis. A comparison of the value of topical diphencyprone and tretinoin gel.

Diphencyprone is a potent topical sensitizer, but is non-mutagenic in the Ames test (unlike dinitroclorobenzene) and remains relatively stable in solution (unlike squaric acid dibutyl ester). Seventeen patients with total loss of scalp hair (eight alopecia totalis, nine alopecia universalis) were treated by maintaining on one side of the scalp an allergic contact dermatitis induced by 2,3 diphenylcyclopropenone-I ('diphencyprone'), and on the other side an irritant contact dermatitis using tretinoin gel (Retin A). After 20 weeks, treatment with tretinoin was stopped and diphencyprone was applied bilaterally for a further 10 weeks. Satisfactory regrowth of terminal hair on the scalp was achieved in only one patient. Eyebrow, eyelash and beard regrowth was achieved in one individual whilst in another, moderate, but not cosmetically satisfactory, scalp regrowth took place. In no patient did regrowth take place at tretinoin treated sites until after diphencyprone was substituted.