An open, randomized, comparative clinical and histological study of imiquimod 5% cream versus 10% potassium hydroxide solution in the treatment of molluscum contagiosum

Abstract

Background: Although molluscum contagiosum (MC) resolves spontaneously, there are several reasons to treat this dermatological disorder.

Objective: To evaluate the safety and efficacy of 5% imiquimod cream versus 10% potassium hydroxide (KOH) solution in treating MC, and to propose the mechanism of cure by observing the histological findings.

Methods: Imiquimod or KOH were applied by the patient or a parent 3 days per week until all lesions cleared. The number of MC lesions was counted and side effects were evaluated at 5 points during the treatment (the initial visit, week 2, week 4, week 8, and week 12). Histological changes were compared between 2 patients of each group, before and after the 2 weeks of application.

Results: In both group, the mean lesion counts decreased all through to week 12, and the reduction in number of lesions were statistically significant in both groups (p <0.005). Over 40% of each group developed local side effects, and no systemic side effects were noted in either group. Before treatment, histological findings showed little or no dermal infiltrates. After treatment, specimens showed dense lymphocytic infiltrates, especially T cells, around the lesions which had resolved.

Conclusion: Both 10% KOH solution and 5% imiquimod cream are effective and safe treatment of MC.

Keywords: Imiquimod; Molluscum contagiosum; Potassium hydroxide.

Fig. 1

Decreased lesions in patients treated with 5% imiquimod cream, (A) before treatment, (B) after 1 month of treatment.

Fig. 2

Decreased lesions in patients treated with 10% KOH solution, (A) before treatment, (B) after 2 weeks of treatment.

Fig. 3

(A~D) Before the treatment. Molluscum contagiosum showed many epidermal cells which contain large, intracytoplasmic inclusion bodies. The surrounding dermis shows little or no inflammatoty reaction (H&E, ×100).

Fig. 4

After 2 weeks of application of 5% imiquimod cream. (A, B) The lesions showed increased lymphocytic infiltrates around and into the lesions (H&E, ×100). (C, D) By use of CD3 stains, T cell markers, cells around the lesion were stained (CD3, ×100).

Fig. 5

After 2 weeks of application of 10% KOH solution. (A, B) The lesions showed increased lymphocytic infiltrates around and into the lesions (H&E, ×100). (C, D) The infiltrated lymphocytes were stained with CD3 (CD3, ×100).