Pigmented actinic lichen planus: a case report
Katarina Đorđević1, Jovan Lalošević1,2, Miloš Nikolić1,2 ✉
1Clinic of Dermatology and Venereology, University Clinical Center of Serbia, Belgrade, Serbia. 2Faculty of Medicine, University of Belgrade, Belgrade, 
Serbia.
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2024;33:159-162
doi: 10.15570/actaapa.2024.19
Introduction
Actinic lichen planus (ALP) is a rare photo-distributed subtype 
of lichen planus (LP) with an incidence estimated at one case per 
million inhabitants per year (1). Over the years, the condition has 
been described under various names, including lichen planus 
tropicus, lichen planus subtropicus, summertime actinic lichenoid 
eruption, and lichenoid melanodermatitis (2). Katzenellenbogen 
was the first to use the term lichen planus actinicus, emphasizing 
the role of UV radiation as the main contributing factor (3). Al-
though the clinical appearance varies from annular plaques and 
melasma-like patches to classic lichenoid papules (4), the histo-
logical findings of ALP almost always exhibit the typical charac-
teristics of classic LP (5, 6). The majority of cases are reported in 
young adult females with darker skin (Fitzpatrick III and IV) of 
Middle Eastern or Indian origin (5–8). Since the first reports in the 
1960s, very few cases have been reported across European coun-
tries (9). The extremely low incidence among whites, even in sun-
ny countries, supports the potential role of genetics as another 
contributing factor (10). Clinical and histological presentation of 
ALP can resemble other photodermatoses, drug eruptions, and 
granulomatous diseases (8, 11–13). Due to an uncertain etiology 
and the rarity of the disease, there are no treatment guidelines 
and there is no consensus on appropriate topical and/or systemic 
therapy. Various strategies have been reported, but hydroxychlo-
roquine with intralesional or topical glucocorticoids and sun-
screens have shown the greatest efficacy (1, 12, 14).
In settings of rare occurrence, with a broad spectrum of clini-
cal presentations and no clear guidelines, and with many cases 
refractory to conventional therapy, ALP may present a significant 
diagnostic and therapeutic challenge.
Case report
A 68-year-old man with Fitzpatrick skin type II presented to our 
clinic with a 9-year history of a mildly pruritic hyperpigmented 
patch on the tip of his nose. He stated that since the onset the 
lesion had gradually increased in size and become more pigment-
ed. Over the years, the patient observed a pattern of slight regres-
sion (lightening) during the winter months and worsening (lesion 
darkening) through the summer months. He denied using any 
drugs or supplements before the onset of the disease. He started 
taking tamsulosin, a treatment for benign prostatic hyperplasia, 
four years after the lesion began. He had no other significant med-
ical history, and he denied using any other systemic medication 
or topical application of any creams or ointments.
Clinical examination revealed a slightly elevated irregular-
shaped violaceous-brown hyperpigmented patch on the tip of 
the nose with discrete central atrophy (Fig. 1). The mucous mem-
branes and nails were unaffected. On dermoscopic examination, 
structureless, irregular brownish-gray pigmentation was present, 
more prominent around the follicular openings, with diffuse pep-
pering and discrete follicular plugging. At the first visit, the pa-
tient rejected a skin biopsy, and he was therefore evaluated clini-
cally and with a detailed history for potential fixed drug eruption 
and sarcoidosis. Angiotensin-converting enzyme and chitotriosi-
dase serum levels were normal, and X-rays were unremarkable. 
Because all these findings and history were inconclusive, the pa-
tient agreed to a skin biopsy.
A punch biopsy taken from the lesion showed atrophy of the 
epidermis with mild hyperkeratosis, focal hypergranulosis, and 
basal vacuolar degeneration. In the dermis, there was scattered 
superficial, perivascular and perifollicular lymphocytic infiltrate
Abstract
Actinic lichen planus (ALP) is a rare photosensitive subtype of lichen planus (LP) with four major forms recognized: annular, pig-
mented (melasma-like), dyschromic, and classic lichenoid. The prevalence is highest among dark-skinned younger females resid-
ing in tropical and subtropical regions. There are very few reports of ALP across Europe, with most of the cases among individuals 
living in warm countries or in people of Middle Eastern and Indian ancestry. We report a case of a 68-year-old white man that 
presented with a 9-year history of a mildly pruritic solitary hyperpigmented patch on the tip of his nose. Histopathological ex-
amination demonstrated signs of classic LP with epidermal atrophy, pigmentary incontinence, and signs of solar elastosis. Based 
on these findings, a diagnosis of pigmented ALP was established. Topical pimecrolimus and tretinoin along with rigorous photo-
protection proved effective, with mild residual hyperpigmentation after 6 months of treatment. Many differential diagnostic pos-
sibilities should be considered for such a lesion. Nevertheless, a biopsy and correlation of histopathological and clinical findings 
can shorten the time from onset to a proper diagnosis. Treating both the hyperpigmented and inflammatory component of this 
dermatosis is necessary, as well as strict long-term photoprotection to prevent recurrences.
Keywords: actinic lichen planus, pigmented lesion, photosensitivity, clinicopathological correlation, topical therapy
Acta Dermatovenerologica 
Alpina, Pannonica et Adriatica
Acta Dermatovenerol APA
Received: 1 May 2024 | Returned for modification: 5 July 2024 | Accepted: 31 July 2024
✉ Corresponding author: milos.nikolic@med.bg.ac.rs
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Acta Dermatovenerol APA | 2024;33:159-162K. Đorđević et al.
with marked pigmentary incontinence, rare melanophages, and 
prominent signs of solar elastosis (Fig. 2).
Based on the clinical presentation, seasonal variations, and 
histopathological findings, a diagnosis of pigmented ALP was 
made. The patient was treated with topical 0.1% mometasone 
furoate ointment twice daily for 2 weeks, followed by 1% pime-
crolimus cream and 0.05% tretinoin cream applied in the morning 
and evening, respectively. The patient was instructed to use topi-
cal sunscreens and to strictly avoid sun exposure. Three months 
after starting the treatment, there was significant improvement in 
terms of infiltration and pigmentation (Fig. 3A). At the last visit, 6 
months after starting the treatment, mild hyperpigmentation per-
sisted (Fig. 3B). Given that our patient responded positively to the 
prescribed treatment combination, with regression of the infiltra-
tion as well as less hyperpigmentation, we continued the therapy 
with rigorous photoprotection.
Discussion
We report a case of the pigmented form of ALP, a rare photosen-
sitive subtype of LP, presenting as a slightly indurated violaceus 
patch on the nose of a 68-year-old male with Fitzpatrick II skin 
type. The condition is highly unusual among whites residing in 
central and northern parts of Europe. Diagnosing ALP can be 
challenging, given that there are no other clinical signs and symp-
toms indicative of lichen or lichenoid dermatoses (4). Because the 
pathogenesis of the onset and relapses of ALP is mostly unknown, 
there is still no consensus on the treatment approach.
The first reports suggested that the condition is restricted to 
tropical and subtropical regions and that it predominantly mani-
fests in younger individuals with darker skin types (7). Racial 
predilection to people of Middle Eastern and Indian origin, rather 
than geographical distribution, favors a genetic basis of the con-
dition (5, 15). However, UV radiation from sunlight and lamps 
seems to be the main trigger in inducing the lesions (9). UV ra-
diation provokes the expression of altered self-antigens on basal 
keratinocytes that are responsible for the recruitment of cytotoxic 
T-cells, resulting in characteristic microscopic features such as 
basal cell vacuolization (14). Supporting the hypothesis of ALP 
being a photosensitive reaction in genetically predisposed indi-
viduals is a case of actinic LP following the lines of Blaschko (15). 
The concept of genetic mosaicism in the acquired Blaschko-linear 
inflammatory dermatoses implies that different genetic composi-
tions within skin cells may result in the presence of various an-
tigens on them. This antigenic mosaicism could then activate a 
mosaic T-cell response to external triggers such as sunlight (16).
Accordingly, the lesions of actinic LP mainly develop on sun-
exposed areas of the face, neck, and forearms, on the dorsa of the 
hands, and on the shins (4, 17). Rarely, unexposed skin areas and 
buccal mucosa can be involved (6). Most patients report onset in 
spring or summer, and improvement or even complete remission 
in winter (18). Four morphological patterns of actinic LP have 
been clinically described in the literature: annular, pigmented 
(melasma-like type), dyschromic, and classic plaque-like type 
(1). Our case was compatible with the pigmented type of actinic 
LP based on the clinical appearance of the lesion. The pigmented 
form, also called the melasma-like type, is characterized by gray 
to brown or black patches ranging in size between 0.5 and 5 cm 
(13) located on the face and neck, with the lateral sides of the fore-
head being the most common site of presentation (1, 6, 18). Un-
like in classic lichen planus, the Koebner phenomenon, scaling, 
and mucosal or nail involvement are not common in the actinic 
variant. Pruritus is minimal or absent (1). Our patient presented 
with a solitary violaceous-brown hyperpigmented patch on the 
tip of the nose, a site rather uncommon for ALP, which led us to 
consider cutaneous sarcoidosis, fixed drug eruption, and discoid 
lupus erythematosus, and differential diagnoses of actinic LP 
among melasma, lentigo maligna, granuloma annulare, polymor-
phous light eruption, pigmented actinic keratosis, and erythema 
dyschromicum perstans (1, 12–14). A detailed medication history 
and seasonal appearance of the lesion excluded the possibility of 
drug-associated eruptions (e.g., amiodarone-induced nose pig-
mentation).
Although dermoscopy might help differentiate actinic LP from 
other pigmented and nonpigmented lesions, its use is limited be-
cause similar patterns are observed in other acquired hypermela-
noses. Data on dermoscopic findings in actinic LP are scarce, but 
so far peripheral or diffuse dots and globules with peppering and 
Figure 1 | A) Slightly infiltrated irregularly shaped violaceous-brown hyperpig-
mented patch on the tip of the nose with discrete central atrophy; B) close-up 
view of the lesion.
Figure 2 | A) Atrophy of the epidermis with basal vacuolar degeneration; in 
the dermis, small melanocytic cells together with melanophages and papil-
lary and mid-dermal perivascular inflammation; chronic actinic damage (solar 
elastosis) was also found (hematoxylin and eosin, original magnification ×40); 
B) inflammatory infiltrate, composed of lymphocytes and histiocytes in peri-
follicular areas (hematoxylin and eosin, original magnification ×40); C) focal 
hypergranulosis (arrow; hematoxylin and eosin, original magnification ×40).
Figure 3 | A) Mild residual pigmentation after 3 months of therapy; B) after 6 
months of therapy.
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Acta Dermatovenerol APA | 2024;33:159-162 Pigmented actinic lichen planus
perifollicular, annular, linear, or homogeneous cloud-like pig-
ment patterns have been reported (13, 19, 20). Gungor et al. (19) 
demonstrated that all 10 ALP lesions analyzed in their study had 
diffuse peppering arising on a brown background with absent 
Wickham striae and a vascular pattern, a finding consistent with 
our case. However, there is a significant overlap of dermatoscopic 
patterns in pigmented actinic LP, melasma, pigmented actinic 
keratosis, erythema dyschromicum perstans, erythromelanosis 
follicularis faciei et colli, and lentigo maligna (20). For instance, 
shared dermatoscopic characteristics of pigmented ALP and pig-
mented AK comprise linear, annular, and granular structures, 
characterized by the coalescence of grayish-brown dots and 
globules around the hair follicles; these have been shown histo-
logically to be due to the presence of aggregates of melanin and 
macrophages in the papillary dermis. Another common shared 
dermatoscopic finding is a subtle homogeneous gray or beige 
halo that surrounds the follicular openings or follicular plugs, 
also known as inner gray halo. The histologic equivalent of this 
feature is the inverted cone of “spared” orthokeratotic epider-
mis, which tends to spread around the follicular openings on the 
surface of the epidermis. When in doubt, clinicians should seek 
additional and specific patterns so far described in some of the 
differential diagnoses. In the aforementioned example, an addi-
tional finding present in pigmented AK, but absent in pigmented 
ALP, is rosettes arranged in a four-leaf clover shape, mainly lo-
calized inside the follicular openings, better visible in polarized 
contact dermoscopy (21). Although more research is required, the 
use of dermoscopy for this group of disorders appears promising 
and may act as a supplementary tool. Nevertheless, histologic ex-
amination remains the gold standard. The histologic features of 
ALP are quite diverse, but mostly similar to those of classic LP: hy-
perkeratosis, hypergranulosis, basal vacuolar degeneration, and 
Civatte bodies are usually present. At the dermal level, there are 
a bandlike lymphocytic inflammatory infiltrate in the superficial 
dermis, melanophages, and marked pigmentary incontinence (1). 
Furthermore, the pigmented form of ALP is often associated with 
signs of actinic damage in the skin such as epidermal atrophy and 
solar elastosis in the dermis (8, 13). The punch-biopsy specimens 
taken from our patient demonstrated significant epidermal thin-
ning with loss of the normal rete ridge pattern with hyperkera-
tosis, focal hypergranulosis, and basal vacuolar degeneration. In 
the dermis, there was sparse subepidermal lymphocyte infiltra-
tion and prominent solar elastosis. In addition, perifollicular and 
periadnexal inflammatory infiltrate was observed, a feature more 
often visible in cutaneous lupus erythematosus. However, patho-
logical studies by Kamyab et al. have suggested that this finding 
is not as rare in patients with actinic LP, reporting it in about 25% 
of cases (6). The variability of histological presentations among 
reports is explained by the difference in the disease duration and 
biopsy site (4).
Several treatment strategies have been reported, but there are 
no clear guidelines in the management. All patients should be 
advised to use high-SPF sunscreens or sunblocks and avoid sun 
exposure because there is a clear relationship to UV radiation 
inducing the lesions and relapses, and a few reports also claim 
spontaneous remission or regression during the winter months 
(2). Intralesional and topical corticosteroids are the first-line treat-
ment, resulting in almost complete resolution of lesions, with 
their only limitation being skin atrophy induced by prolonged use 
(13, 18). Calcineurin inhibitors act by decreasing the aforemen-
tioned T-lymphocyte activation and are safe for long-term use. 
Topical pimecrolimus and tacrolimus have resulted in major im-
provement and no recurrence of the lesions, as reported in several 
articles (15, 22, 23). In refractory and rapidly progressive cases, an-
timalarials (1), cyclosporine (24), and systemic corticosteroids (23) 
have been used as effective treatment options. Although acitretin 
was proved to be a successful treatment for classic LP, its role in 
actinic LP is not completely clear due to variable results (1, 17, 18). 
Residual hyperpigmentation, as seen in our patient, is very 
common (25) and could be associated with the gray and blue hue 
seen on dermoscopy. These are signs of deeper deposition of pig-
ment in the dermis, which is typically more persistent and less 
responsive to treatment (20). After the initial short-term treatment 
with a high-potency topical corticosteroid, our patient was pre-
scribed pimecrolimus cream due to its action on the inflammatory 
component of the disease. Topical tretinoin was added to combat 
the residual hyperpigmentation and signs of chronic actinic dam-
age.
Conclusions
To the best of our knowledge, this is the first reported case of 
ALP in this part of Europe. Genetic susceptibility could be the 
reason behind this rare type of photosensitivity in our patient. In 
addition to strict photoprotection, due to the possible role of T-
lymphocytes in the pathogenesis of ALP, we opted for long-term 
treatment with topical calcineurin inhibitor combined with topi-
cal retinoid to address hyperpigmentation and signs of chronic 
actinic damage.
Funding
This study was supported by the Ministry of Education and Sci-
ence of the Republic of Serbia (grant no. 175065).
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