Experimental inoculation of dermatophytes on psoriatic skin.

Two dermatophytic agents, Trichophyton rubrum and Trichophyton mentagrophytes were used in the experimental inoculation of psoriatic lesions in 27 volunteer patients (13 males and 14 females with an age range from 17 to 72 yr). T. rubrum was inoculated in 14 patients and T. mentagrophytes (varietas granulare) in 13. For purposes of control in each patient the same agent was also inoculated on healthy skin. Results were noted once a week for a period of 1 mo. A positive response was found in 12 of the 14 patients inoculated with T. rubrum but only in 4 of the 13 inoculated with T. mentagrophytes. Healthy skin was found to have a positive response in only 5 cases, in 4 with T. rubrum, and in 1 with T. mentagrophytes. These results confirm the possibility of invasion of psoriatic lesions by dermatophytes and suggest that the coexistance of psoriasis and dermatophytic infection may be not always purely coincidental. The importance of the awareness of the presence of mycotic lesions and their possible spread with the application of steroid ointments under occlusive dressings in a psoriatic patient is stressed.