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| Journal of the New Zealand Medical Association,
10-August-2007, Vol 120 No 1259
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Self-applied treatment of persistent plantar wart
with 5% imiquimod cream
Plantar warts are predominantly caused by human
papillomavirus (HPV) types 1, 2 and 4.1
Three-quarters of plantar warts spontaneously regress within 2 years, however
they can persist and may be resistant to
treatment.2
There are currently various approaches in the treatment of
plantar warts including cryotherapy, salicylic acid, cytotoxic agents,
immunotherapy, surgical excision, and laser therapy. The recurrence rate
following these treatments can be high due incomplete eradication of the virus
from the site of infection. We describe a case of successful treatment of a
recalcitrant plantar wart using 5% imiquimod
(Aldara™) cream in combination with
salicylic acid and duct tape occlusion.
A healthy 26-year-old male presented with a 2-year history
of plantar warts measuring approximately 2 cm in the longest dimension on the
left foot and 0.4 cm on the right foot. The larger wart had previously been
treated by cryotherapy with liquid nitrogen and with topical administration of
podophyllin and salicylic acid, which were all ineffective. The wart continued
to grow and caused discomfort when pressure was applied.
The treatment regimen, which was applied only to the wart on
the left foot, involved initial destruction of the thickened surface skin with
topical application of salicylic acid for 2 weeks. The 5% imiquimod cream was
then applied daily at a dose of 12.5 mg/week for 6 weeks, with duct tape
occlusion.
The patient experienced some swelling, redness, and itching
at the site of infection during treatment. A reduction in lesion size was
observed 2 weeks following the initiation of the treatment with imiquimod. After
8 weeks of treatment there was near complete resolution of the wart with only
some flaky surface skin remaining.
Three weeks after the imiquimod was last applied, the
treated wart had completely healed and the untreated wart on the right foot had
spontaneously resolved. At 19-months follow-up there was no evidence of
recurrence of either wart. See Figure 1.
Figure 1. Presentation of recalcitrant plantar
warts. Plantar wart on the left foot (A) and a smaller wart on the right foot
(H). Destruction of the thickened skin of the left foot lesion observed 2 weeks
post-salicylic acid treatment (B). Lesion on left foot following commencement of
imiquimod treatment: 4 days (C); 2 weeks (D); 6 weeks (E); 8 weeks (F).
Clearance of the wart on the left foot (G), and the right foot (I), observed 3
weeks after completion of imiquimod treatment. The scale bar on (A and H)
represents 1 cm.
 DiscussionIn this report, we demonstrate the successful treatment of a
plantar wart with imiquimod in combination with salicylic acid and duct tape
occlusion. Imiquimod is a topical immune modulator licensed for the treatment of
anogenital warts. It functions through toll-like receptor-7-mediated activation
of the immune.3
Imiquimod also stimulates migration of Langerhans cells
(LC), the antigen presenting cells of the epidermis, enhancing presentation to
T-cells.4 It has been proposed that
HPV-specific cell-mediated immunity is activated, reducing recurrence of
warts.5
In this case, complete resolution of the untreated wart at a
site distant from the treated infection suggests that a systemic response
against HPV was activated.
Skin thickening may contribute to the recalcitrance of
plantar warts to treatment. Initial tissue destruction with salicylic acid may
have aided the penetration of the imiquimod into the infected tissue. In
addition, duct tape occlusion has been reported to promote resolution of
warts.6 It has been proposed that duct tape
induces a proinflammatory response at the site of application, increasing
infiltration of immune cells, including LC.7
This may have contributed to the efficacy of the treatment regimen used
here.
Although the patient experienced a mild inflammatory
response, there were no systemic or long-term adverse effects following the
imiquimod treatment. Cost may be a limitation of imiquimod treatment for plantar
warts, however to minimise costs, imiquimod was used sparingly and a single-use
packet (12.5 mg) was used for each week of treatment.
Plantar warts are frequently persistent and debilitating and
in severe cases can cause hospitalisation.8
This study shows that imiquimod in combination with salicylic acid and duct tape
occlusion can be used to treat plantar warts.
Cheng-Mee (Jimmy) Leong
PhD candidate Virus Research Unit, Department of Microbiology and Immunology University of Otago, Dunedin Jane Tarbotton
General Practitioner Mornington Health Centre, Dunedin Merilyn Hibma
Senior Research Fellow Department of Microbiology and Immunology University of Otago, Dunedin (merilyn.hibma@stonebow.otago.ac.nz) References:
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