Blurred lines – Erythema Dyschromicum Perstans and Lichen Planus Pigmentosus
Tuesday, October 20, 2015
The terms lichen planus pigmentosus (LPP), erythema dyschromicum
perstans (EDP) and idiopathic eruptive macular pigmentation (IEMP)
are often used interchangeably, and if one examines the medical
literature, what is referred to as LPP in one publication is termed
EDP or IEMP in another. Even pigmentary disorder experts around the
world differ in their opinion about exactly what clinical and
histopathological features constitute these entities.
IEMP is a rare pigmentary disorder described initially by Degos et
al. Given it is rare and seen predominantly in children and
adolescents, it will not be discussed here. Despite the controversy
that surrounds EDP and LPP, there appear to be a few key
differences between the two conditions (Table 1).
EDP tends to present in the second to third decade of life, and is
seen most commonly in those with intermediate skin phototypes (e.g.
Latin Americans and Asians). This is in contrast to LPP, which is
usually noted in slightly older Indian and Middle Eastern people.
While EDP usually presents with asymptomatic blue-gray discrete
lesions with erythematous borders, LPP may present with itchy,
scaly brown-gray macules without erythematous borders. EDP tends to
involve photo-protected sites, unlike LPP, and the histology of
these conditions reflects its clinically appearance. Deep dermal
melanin deposition in EDP gives rise to its characteristic
blue-gray hue, while superficial melanin in LPP results in its
Table 1. Comparison between EDP and LPP.
Second to third decade of life
Third to fourth decade of life
May have itch and scale
Lacks erythematous border
Discrete lesions (larger than LPP) early on then diffuse
Multiple small and large macules
Does not involve mucosal surfaces
May involve mucosal surfaces
Dermal melanophages, mild lichenoid reaction and mild
Dermal melanophages, lichenoid change (band-like) on biopsy of
early lesions (may not be seen later in disease course)
Melanin in deep dermis
Melanin in superficial dermis
Erythema dyschromicum perstans (EDP)
EDP (also known as ashy dermatosis) was first described by
Ramirez in El Salvador in the 1950s.1 This acquired
disorder of hyperpigmentation is most commonly seen in women and in
those with more deeply pigmented skin, including Latin Americans
and Asians.2 While most studies cite onset in the second
to third decade, the most recent case review of patients in Korea
revealed a slightly later onset (third to fourth decade).
Figure 1. Erythema dyschromicum perstans (EDP).
EDP presents with widespread well-demarcated and slowly expanding
blue-gray macules. The lesions rarely cause mild itch and
demonstrate an erythematous border in the acute inflammatory phase.
While involvement of the face, neck, limbs, and trunk has been
described most commonly, a unilateral presentation has also been
The histological features of EDP depend on the age of the lesion
biopsied. Early on, papillary dermal edema and basal layer
vacuolation with a perivascular infiltrate is noted. Later, the
inflammatory cell infiltrate becomes sparse, but melanin
incontinence and melanophages are noted in large amounts in the
dermis, particularly the deep dermis.2
Unfortunately, as the name suggests, the condition is chronic and
a challenge to treat. Unsurprisingly, while hydroquinone and
tretinoin are helpful in pigmentary conditions, such as melasma and
post-inflammatory hyperpigmentation, they have not demonstrated
significant lightening in EDP, likely due to the dermal location of
abnormal pigment.4 Dapsone has been reported to
lighten pigmentation and even completely resolved it when taken for
8-12 weeks at a dose of 100 mg daily.5,6 While
clofazamine demonstrated improvement in a small study (100 mg
daily), the anecdotal experience among pigmentary disorders experts
globally has not been so positive.7 Unfortunately,
while many other treatments have been evaluated, including topical
steroids and chloroquine, none have resulted in appreciable
lightening. Most recently, laser surgery has been studied by a
group in the Netherlands, who concluded fractionated laser was
unsuccessful for treatment of EDP.8 Examination of
the literature highlights the need to more clearly define this
entity and to thoroughly evaluate the efficacy of treatment
Lichen planus pigmentosus (LPP)
LPP is a rare variant of lichen planus usually seen in
middle-aged individuals with more deeply pigmented skin (e.g. South
Asians, South-East Asians and the Arabic population). Though this
is most commonly seen in photo-exposed sites, such as the head
(forehead and temples) and neck, the symmetrical brown to
gray-brown macules and patches are often seen in skin folds such as
the axillae (LPP-inversus)9 and occasionally the
mucosa. Unlike EDP, LPP lacks clinical signs of inflammation
and does not have lesions with erythematous borders.
The exact cause of LPP is unknown, although ultraviolet light has
been implicated due to the location of the lesions. Mustard and
amla oils have been reported as possible causes in some
retrospective studies.10 These oils are used
routinely in India in hair care preparations, massage oils and for
cooking. Allyl thiocyanate is a potential photosensitizer in
mustard oil and may be a pathogenic agent in LPP.
Figure 2. Lichen planus pigmentosus
(LPP). Histopathological evaluation of lesional skin
reveals epidermal atrophy and basal layer vacuolation with a
perivascular lymphocytic infiltrate. The dermal melanophages are
situated in the superficial dermis in LPP in contrast to EDP in
which they are in the deep dermis.
LPP undoubtedly presents a therapeutic challenge. While some
cases gradually resolve over many months, many persist for years or
even decades. Sunscreen and sun-protection are key components in
the treatment of LPP. Various small studies reveal topical
tacrolimus (0.03% twice per day), topical and systemic
corticosteroids and topical vitamin A may be helpful in
LPP.11 Combinations of the above-mentioned
therapies have also been studied to prevent progression of LPP, but
advances clearly need to be made in the LPP therapeutics arena.
The blurred lines between LPP and EDP clearly demonstrate the need
for a large scale, multi-center study to further delineate these
two conditions etiologically, morphologically and histologically. A
summary of the treatment options currently used in the management
of EDP and LPP are shown below in Table 2. However, large,
double-blinded randomized studies are needed to more accurately
assess the success of therapeutic interventions.
Table 2. Summary of therapeutic options for EDP and
Photoprotection + avoid potential triggers
Potent topical corticosteroids
Potent topical +/- oral corticosteroids - especially if disease
is actively expanding, itching
Hydroquinone 4% or more
Hydroquinone 4% or more
- Ramirez, CO. Los cenescientos: problema clinic. Proceedings of
the first Central American Congress of Dermatology. San Salvador:
El Salvador, 1957;122-30.
- Chang SE, Kim HW, Shin JM, et al. Clinical and histological
aspect of erythema dyschromicum perstans in Korea: A review of 68
cases. J Dermatol 2015;42:1-5.
- Imanishi H, Tsuruta D, Kobayashi H, et al. Two cases of
unilateral ashy dermatosis. Case Rep Dermatol
- Stratigos AJ, Katsambas AD. Optimal management of recalcitrant
disorders of hyperpigmentation in dark-skinned patients. Am J
Clin Dermatol 2004;5:161-8.
- Bahadir S, Cobanoglu U, Cimsit G, et al. Erythema dyschromicum
perstans: response to dapsone therapy. Int J Dermatol
- Kontochristopolus G, Stavropoulus P, Panteleos D, et al.
Erythema dyschromicum perstans: response to dapsone therapy.
Int J Dermatol 1998;37:790-9.
- Global Forum on Ashy Dermatosis, Lichen planus pigmentosus,
Erythema Dyschromicum Perstans, Eruptive Macular Pigmentation,
Vancouver, Canada. June 2015.
- Kroon MW, Wind BS, Meesters AA, et al. Non-ablative 1550 nm
fractional laser therapy not effective for erythema dyschromicum
perstans and postinflammatory hyperpigmentation: a pilot study.
J Dermatolog Treat 2012;23:339-44.
- Gaertner E, Elstein W. Lichen planus pigmentosus-inversus: case
report and review of an unusual entity. Dermatol Online J
- Kanwar A, Dogra S, Handa S, et al. A study of 124 Indian
patients with lichen planus pigmentosus. Clin Exp Dermatol
- Al-Mutairi N, El-Khalawany M. Clinicopathological
characteristics of lichen planus pigmentosus and its response to
tacrolimus ointment: an open label, non-randomized, prospective
study. J Eur Acad Dermatol Venereol 2010;24:535-40.