A prospective study of cutaneous intolerance to topical mechlorethamine therapy in patients with cutaneous T-cell lymphomas

Objective: To study the exact frequency and the histological features of cu taneous intolerance to mechlorethamine (CIM) hydrochloride therapy in patie nts with cutaneous T-cell lymphomas, including Langerhans cell histiocytosi s. Design: A multicenter prospective study was conducted from January 1, 1994, to May 31; 1996, in 12 different hospitals in France. Patients: Of the 52 patients with cutaneous T-cell lymphomas or Langerhans cell histiocytosis, 35 were men and 17 were women, aged 18 to 87 years. Of the 52 patients, 35 had mycosis fungoides, 8 had nonepidermotropic cutaneou s lymphoma, 7 had lymphomatoid papulosis, 1 had Sezary syndrome, and I had Langerhans cell histiocytosis. Methods: Patients were treated with topical applications of a 0.02% aqueous solution of mechlorethamine. The diagnosis of CIM was determined by the pr esence of erythema and pruritus. Patients who developed CIM underwent close d patch testing with three 10-fold dilutions of 0.02% mechlorethamine solut ion. A positive patch test result was the presence of erythema and pruritus , a weak result was the presence of simple erythema without pruritus, and a negative result was the absence of erythema and pruritus. Skin biopsy spec imens from patients with positive patch test results were obtained in patie nts who developed CIM. The biopsy specimens were reviewed, and the results determined by 2 pathologists (E.T. and J.W.). The histopathological finding s were classified in 3 categories: (1) spongiotic dermatitis, (2) irritant dermatitis, and (3) insignificant or normal. In September 1998, the referri ng physicians were contacted if mechlorethamine therapy had been continued in patients with CIM. Results: Of the 52 patients, 43 were evaluated for tolerance to mechloretha mine therapy. Of the 43 patients, CIM developed in 23, from 4 days to 9 mon ths after the initiation of mechlorethamine therapy. Of those 23 patients, CIM developed within 3 months in 21 and within 1 month in 13. Closed patch tests were performed in 21 of the 23 patients who developed CIM. The result s of the patch test were positive in 12, weak in 4, and negative in 5. Of t hese 21 patients, 14 skin biopsy specimens were obtained in 14 different pa tients who had positive or weak patch test results. The specimens showed hi stological features that were consistent with spongiotic dermatitis in 9 pa tients, irritant dermatitis in 2, and insignificant or normal in 3. All 9 p atients with histological features of spongiotic dermatitis discontinued me chlorethamine therapy. All 5 patients without histological features of spon giotic dermatitis were able to resume mechlorethamine therapy. These result s do not correlate with those of previous study results. Conclusions: Mechlorethamine therapy is a cost-effective and easily adminis tered treatment for cutaneous T-cell lymphomas. Our study shows that allerg ic dermatitis caused by mechlorethamine therapy is an early and frequent ad verse reaction in patients with cutaneous T-cell lymphomas. The most common histological feature of patients with CIM is spongiotic dermatitis.