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CLINICAL REPORT
Effectiveness of 5% Topical Imiquimod for Lentigo Maligna
Treatment
Darryl C. K. S. TIO 1 , Catherine VAN MONTFRANS 2 , Claire G. H. RUIJTER 1 , Rick HOEKZEMA 1 and Marcel W. BEKKENK 1
1
Department of Dermatology, Amsterdam University Medical Centers, Vrije Universiteit Medical Centre, Amsterdam, and 2 Department of
Dermatology, Erasmus Medical Centre, Rotterdam, The Netherlands
Lentigo maligna (LM) is treated to prevent progres-
sion to lentigo maligna melanoma (LMM). Surgery is
the gold standard, but an alternative treatment is off-
label topical imiquimod. The aim of this study was to
evaluate the effectiveness of 5% topical imiquimod
treatment for lentigo maligna. In the period 2007–
2017 57 patients with lentigo maligna were trea
ted with off-label topical imiquimod once daily for 12
weeks. Complete clinical clearance was observed in 48
patients (84.2%) and partial clearance in 3 patients
(5.3%). Three patients (5.3%) showed no response
and another 3 patients (5.3%) stopped treatment due
to side-effects. After 4.5 years, during follow-up, one
patient developed a lentigo maligna melanoma, which
was subsequently excised. Treatment with topical
imiquimod resulted in complete clearance of lentigo
maligna in 48 out of 57 patients (84.2%). Topical imi-
quimod is an acceptable treatment option for patients
with lentigo maligna who prefer topical treatment to
surgery or radiotherapy.
Key words: lentigo maligna; topical imiquimod; melanoma.
Accepted Jun 18, 2019; E-published Jun 24, 2019
Acta Derm Venereol 2019; 99: 884–888.
Corr: Darryl Tio, Department of Dermatology, Amsterdam University
Medical Centers, Vrije Universiteit Medical Centre, De Boelelaan 1117,
1081HV Amsterdam, The Netherlands. E-mail: [email protected]
L
entigo maligna (LM) is considered a type of me-
lanoma in situ. It is prevalent in a predominantly
elderly population with a fair skin type. LM typically
occurs on chronic sun-exposed skin, such as the head
and neck area, where critical anatomical structures are
located. Elderly patients often have multiple comorbi-
dities and, as a consequence, clinical management may
be challenging. Several studies have shown an increased
incidence of LM over recent decades (0.54 LM/100,000
patient years to 1.99 LM/100,000 patient years) (1–4).
Treatment of LM is recommended in order to prevent
progression to lentigo maligna melanoma (LMM), which
can metastasize. The true progression rate is unknown,
but a recent epidemiological study describing 10,545 LM
and 124 LMM patients reported that the cumulative risk
of LMM developing after a LM on any location after 25
years is 2.0–2.6%. The progression of individual lesions
could not be evaluated in this study (1).
According to the current European Consensus Gui-
deline (5), surgical excision is the gold standard for
doi: 10.2340/00015555-3241
Acta Derm Venereol 2019; 99: 884–888
SIGNIFICANCE
Lentigo maligna is treated to prevent progression to lentigo
maligna melanoma. The current treatment of choice for len-
tigo maligna is surgical excision. Topical imiquimod is an al-
ternative option. In this study, topical imiquimod treatment
was successful in 84.2% of patients with lentigo maligna.
treatment of LM. Alternative treatment options, such as
off-label topical imiquimod 5%, radiotherapy, or watch-
ful waiting, are mentioned in the guideline, but there is
no recommendation on their application (5). Surgical
excision of larger lesions can result in disfiguring scars
or functional impairment, and radiotherapy could poten-
tially cause secondary malignancies or radiodermatitis
(6, 7). Off-label topical imiquimod has the advantage of
providing a good cosmetic outcome and it is easy to use
for elderly patients (8).
The reported response rate to off-label topical imiqui-
mod for LM varies between 37.0% and 78.6% (9–12).
This wide range of response rates could be due to the
use of different treatment regimens.
A survey performed by our group among 415 derma-
tologists in Europe showed that non-surgical options are
used quite often. Of the respondents, 17.0% indicated
that they use radiotherapy, 30.6% topical imiquimod,
and 19.6% watchful waiting when treating LM patients
>70 years of age (13).
Patients with LM have been treated with off-label
topical imiquimod 5% since 2007. The patients recrui-
ted for this cohort between 2007 and 2012 have been
described previously by Kirtschig et al. (8), who treated
27 patients with topical imiquimod, of whom 20 (74%)
showed complete clinical and histological clearance
with a mean follow-up of 39 months. The current study
expands this cohort with 30 additional patients with LM
treated between 2012 and 2017.
The aim of this study was to analyse all patients
with LM treated prospectively with off-label topical
imiquimod at our centre between November 2007 and
December 2017, in order to evaluate the effectiveness
of this treatment. Data were collected retrospectively by
reviewing clinical records.
METHODS
Patients were usually referred to our academic referral centre
when they were not eligible for surgical treatment or did not want
This is an open access article under the CC BY-NC license. www.medicaljournals.se/acta
Journal Compilation © 2019 Acta Dermato-Venereologica.