Evaluation of a 1-h exposure time to mechlorethamine in patients undergoing topical treatment

Mechlorethamine is frequently used in the treatment of cutaneous lymphoma, but its application is limited in 30-80% of cases because of cutaneous intolerance. Reducing the concentration to avoid this side-effect has been only modestly successful.

To investigate whether a shorter application period could reduce the frequency of intolerance.

In an open prospective study in 39 patients with cutaneous T-cell lymphoma or parapsoriasis, mechlorethamine was applied according to the usual practices of the participating physicians (number of weekly applications, treatment confined to lesions or performed over the entire body) and then washed off after 1 h in all cases.

Cutaneous intolerance was observed in 19 of 39 patients (49%). Six of these patients showed allergic contact dermatitis to mechlorethamine after a mean period of 9.3 weeks, while the other 13 developed irritant contact dermatitis after a longer period. Cutaneous intolerance did not differ significantly according to the number of applications per week or the extent of body area treated. The therapeutic response rate was 69%, and no difference in therapeutic efficacy was noted between daily and intermittent applications.

Comparison with published studies showed no significant difference in the number of cases of cutaneous intolerance after short-term application, although their occurrence was delayed. Therapeutic response was decreased appreciably by short-term application as compared with results in the literature.