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SKIN
September 2022 Volume 6 Issue 5
(c) 2022 THE AUTHORS. Published by the National Society for Cutaneous Medicine.
451
SKIMages
Erythrasma Under Wood’s Lamp and the “Coral-Red” Glow
Danny Zakria, MD, MBA1, Nicholas D. Brownstone, MD2, McKenzie A. Dirr, BA, BS3, Darrell
Rigel, MD, MS4
1 National Society for Cutaneous Medicine, New York, NY
2 Department of Dermatology, Temple Health, Philadelphia, PA
3 Medical University of South Carolina, Charleston, SC
4 Department of Dermatology, Mount Sinai Icahn School of Medicine, New York, NY
We present a case in which a 54-year-old
male with Fitzpatrick skin type II presented
to clinic with well-circumscribed dark brown
patches with surrounding scale in his bi-
lateral inguinal folds. He reported that he
first noticed the rash about two weeks prior
to presentation and applied OTC anti-fungal
creams with no improvement. He stated that
he has never had a similar rash before, and
he noted that the only associated symptom
was occasional pruritus. Examination with
Wood’s lamp revealed a bright “coral-red”
fluorescence (Figure 1) and helped confirm
the diagnosis of erythrasma.
Erythrasma is a cutaneous bacterial
infection most commonly caused by
Corynebacterium minutissimum.1
Corynebacterium minutissimum is a Gram-
positive bacillus that constitutes the normal
Figure 1. Coral red fluorescence characteristic
of erythrasma
SKIN
September 2022 Volume 6 Issue 5
(c) 2022 THE AUTHORS. Published by the National Society for Cutaneous Medicine.
452
microflora of the skin.2 It has a predilection
for moist areas of the body such as the
axillae, inframammary folds, interdigit
spaces, and the intergluteal cleft.1 C.
minutissimum produces a chemical called
coproporphyrin type III, which leads to the
characteristic “coral-red” glow when
examined under Wood’s lamp.2 Importantly,
bathing can remove the porphyrin and lead
to a false-negative result.2 Erythrasma
classically presents as well-demarcated
dark-brown macules and later coalesces into
larger patches in intertriginous skin.3 The
rash can be confused with other common
pathology including candidiasis,
dermatophytosis, pityriasis versicolor, and
inverse psoriasis.
Candidiasis is a fungal infection most
commonly caused by Candida albicans.1
The rash is typically erythematous and scaly
with evidence of satellite lesions.
Dermatophyte infections can also present as
erythematous and scaly plaques. Both
candidiasis and dermatophyte infections can
be identified using potassium hydroxide
preparation.1 Of note, approximately 30% of
patients with interdigital erythrasma may
have a coexisting dermatophyte or candida
infection. Pityriasis versicolor lesions can be
hyperpigmented or hypopigmented but
usually do not feature scale or well-
demarcated borders as seen in erythrasma.
Inverse psoriasis presents as an
erythematous, non-scaly plaque in
intertriginous lesions. Wood’s lamp offers a
quick and non-invasive method of
diagnosing erythrasma and distinguishing it
from these other similar conditions.
There are several treatment options for
erythrasma including both topical and
systemic therapy. Topical therapy consists
of clindamycin, fusidic acid, mupirocin, and
Whitfield’s ointment while systemic therapy
includes oral clarithromycin, erythromycin,
and tetracycline.4 There is no consensus on
optimal first-line agent, but topical therapy is
generally preferred to limit adverse effects.1
For intertriginous disease, it is important to
add a topical agent, often in conjunction with
systemic therapy, in order to obtain
clearance.4 While there is limited data on
duration of treatment, most studies suggest
a 2-week course. A thorough HPI, high
index of suspicion and appropriate
use/interpretation of the Wood’s lamp exam
can allow for quicker diagnosis and effective
therapy.
Conflict of Interest Disclosures: None
Funding: None
Corresponding Author:
Danny Zakria, MD, MBA
National Society for Cutaneous Medicine
One Harbor Square Suite 325
Ossining, NY 10562
Email: dzakria13@gmail.com
References:
1. Forouzan P, Cohen PR. Erythrasma Revisited:
Diagnosis, Differential Diagnoses, and
Comprehensive Review of Treatment. Cureus.
2020;12(9):e10733. Published 2020 Sep 30.
doi:10.7759/cureus.10733
2. Chen D, Ferringer TC. Red-brown patches in the
groin. Cutis. 2018;101(6):416-420.
3. Riquelme IL, Moyano EG. Axillary and inguinal
erythrasma. CMAJ. 2021;193(39):E1535.
doi:10.1503/cmaj.210310
4. Holdiness MR. Management of cutaneous
erythrasma. Drugs. 2002;62(8):1131-1141.
doi:10.2165/00003495-200262080-00002
