Pitted Keratolysis - Abdel Hamid Derm Atlas
Pitted Keratolysis - Abdel Hamid Derm Atlas
Pitted keratolysis, erythrasma, trichomycosis appear to be
related to cortyneforms or dephteroids
The Corynebacteria are a diverse
group of gram-positive bacilli
which include Corynebacterium
diphtheriae as well as a
bewildering number of species
that are found on the skin as part
of the normal flora. These latter
organisms are usually referred to
as diphtheroids or coryneforms.
Three skin conditions appear to
be related to an overabundance of
these coryneforms: pitted
trichomycosis. Interestingly, all
three have been reported to
coexist in the same person.
Gram Stain from the Blood agar
showing characteristic Gram-positive
short rods with Chinese letter
arrangement of the diphtheroid
Non-diphtherial Corynebacteria, which are
also referred to as Diphtheroids, are a
widely diverse collection of bacteria. Up to
now, the pathogenic potential of coryneform
bacteria has been underestimated. Although
frequently considered as contaminants,
these organisms have been associated with
invasive disease, particularly in
immunocompromised patients. Species like
C. amycolatum, C. jeikeium, C.
minutissimum, and C. urealyticum are being
reported with increasing frequency in recent
years. These organisms have been
implicated in multiple infections like catheterassociated blood stream infections,
endocarditis, prosthetic valve infections,
meningitis, neurosurgical shunt infection,
brain abscess, peritonitis, osteomyelitis,
septic arthritis, urinary tract infections,
empyema, and pneumonia
Pitted keratolysis was first reported in a
Ceylonese patient in 1910, by Castellani
under the term "Keratoma plantare
sulcatum", a disease limited to the soles and
characterized by small pits which coalesced
and formed sulci. In 1930 Acton and
McGuire described eight cases of Keratoma
plantare sulcatum from Bengal. They stated
that the pits were associated with an
organism belonging to the actinomycetes
group and named it Actinomyces
keratolytica sp. nov . Acton and McGuire
renamed the disease "Keratolysis plantare
sulcatum", since the condition in reality is a
partial loss of the stratum corneum rather
than a hyperkeratosis as Castellani's
"Keratoma" implied. In 1931, Acton and
McGuire ( Ind. M. Gazette 66: 65,
1931)suggested that Actinomyces
keratolytica was the causative agent. Zaias
et al (Arch. Derm. 92: 151, 1965), observing
the erosion of the horny layer of the plantar
surfaces, assigned the condition its current
name, "Pitted keratolyis."
10 toes on one foot.
• This condition is characterized
by numerous shallow, discrete
pits on the plantar surface of
the feet, usually in the weightbearing areas. Although the
condition is asymptomatic,
there is usually hyperhidrosis
and the feet may be
malodorous. Painful erosions
may occur. The condition is
caused by Micrococcus
species. Topical clindamycin or
topical erythromycin is the
treatment of choice.
What is the cause of pitted keratolysis?
Pitted keratolysis is caused by several bacterial
species, including corynebacteria, Dermatophilus
congolensis, Kytococcus sedentarius, actinomyces
In moist conditions, the bacteria proliferate. The
pitting is due to destruction of the horny cells
(stratum corneum) by protease enzymes produced
by the bacteria.
The bad smell is due to sulfur compounds produced
by the bacteria.
How is the diagnosis of pitted keratolysis
Pitted keratolysis is usually diagnosed clinically.
Swabs may be helpful to identify causative
organisms, and skin scrapings are often taken to
exclude fungal infection. The diagnosis is
sometimes made by skin biopsy revealing
characteristic histopathological features of pitted
Treatment of pitted keratolysis
Pitted keratolysis can be successfully treated with
topical antibiotics such as fusidic acid cream, or
with oral erythromycin.
It will quickly recur unless the feet are kept dry.
Pitted keratolysis forming sulci on the
Pitted Keratolysis is caused by
Actinomyces or Micrococcus.
Pitted keratolysis with hyperkeratosis
on the heel.
Classic pits of pitted keratolysis on the
plantar aspect of the phalanges.
A large plaque-like lesion of Pitted
keratolysis on the large toe.
A case of inflammatory pitted
pitted keratolysis or keratolysis punctata caused by Corynebacterium of Taplan.
, Histological evaluation of hematoxylin and
eosin (H&E)–stained plantar skin reveals a
crater limited to the stratum corneum (see
the image below).
Histopathology reveals a crater limited to
the thick stratum corneum of the epidermis.
The microorganisms, cocci, and filamentous
forms may be seen with H&E staining, but
they are detected more easily with Gram
stain, periodic acid-Schiff stain, or
methenamine silver stain. In 2000, Wohlarb
et al reported 2 histologic types. The
superficial minor type is coccoid bacteria
found extracellularly on the surface of the
stratum cornea. The classic or major type is
coccoid and septated bacterium forms
intracorneocytically in the horny layer. In
patients with associated foot pain and with
erythematous-to-violaceous macular lesions
and pits, histological examination reveals
only a mild dermal inflammatory reaction. In
2000, de Almeida et el studied pitted
keratolysis with electron microscopy and
noted transverse septated bacterium in
tunnellike openings on the floor of the pits.
Histopathology reveals a crater limited to the thick stratum corneum of the
The use of the VOLAR CORNEAL BIOPSY (VCB), i.e., the use of the cornified scrapings
or clippings from the foot (or hand) for histologic examination, instead of a KOH
• Not only fungi can be
identified. It is not
minutissimum, the agent
of the underestimated
pitted keratolysis of the
soles, can be detected.
The defining thin granules
and filaments making the
diphtheroid will stand up
in the PAS stain
Subungual Horn, Filamentous
Corynebacteria, PAS Stain
Erythrasma is a bacterial infection caused by
Corynebacterium minutissimum (Gram positive
bacteria). , Obesity& diabetic people are more
likely to develop Erythrasma infection caused by
The infection is more common in people who live in
warm climate. The predisposing factors that cause
Erythrasma are obesity, diabetes, poor hygiene,
hyperhidrosis and age. .
Scraping culture test for confirming the infection
may be needed. Wood’s lamp investigation is done
for diagnosing the illness. UV rays of the lamp when
passed on to the infected skin layer, makes it coral
Taking antibiotic medications like erythromycin can
cure the bacterial infection. Topical ointments that
contain fusidic acid and imidazole are prescribed for
controlling infection. Antibacterial drugs and antiinfective medications are given for the patient
depending on the intensity of infection and his
health condition. Erythromycin, Clarithromycin and
Miconazole are prescribed for controlling infection
The pink-red fluorescence of
corynebacteria, an infection of the
body folds known as erythrasma,
shown under a "woods lamp" in a dark
Erythrasma is typically located in moist
Under the arms (axillae)
In the groin and inner thighs
Between the toes, especially between
the 4th and 5th toes
Predisposing conditions to
Gram Stain from the Blood agar showing characteristic Gram-positive
short rods with Chinese letter arrangement of the diphtheroid
Erythrasma is a cutaneous bacterial infection caused by
Corynebacterium minutissimum. It was named in 1961
and is a lipophilic, Gram-positive, non–spore-forming,
aerobic, catalase-positive diphtheroid that makes up to
50% of the normal flora of the skin.
Erythrasma is a common infection present in the toe webs
of up to 44% of diabetics; it is also seen in patients with
advanced age, obesity, poor hygiene and hyperhidrosis.
Erythrasma is the most common interdigital infection of
the foot, presenting as fissuring, scaling and maceration
of the web spaces.
Erythrasma typically affects warm and moist
intertriginous areas such as the axilla, groin and
inframammary area. It presents as a confluent brownish
patch, which later develops into a red-brownish plaque
with minimal scale that is usually asymptomatic but can
be pruritic. In addition to erythrasma, C. minutissimum
has less commonly caused abscess formation,
bacteremia, catheter-related infection and ophthalmologic
Erythrasma is often mistaken for tinea corporis.
Therefore, a negative KOH examination to exclude
dermatophytosis may be helpful.
Erythrasm can be diagnosed by visualizing coral-red
fluorescence under Wood’s light examination of the
effected area. This color results from the porphyrins
produced by C. minutissimum.
Hematoxylin and eosin staining of a skin biopsy may
appear normal. However, the Gram, the periodic acidSchiff and the methenamine silver stains reveal the rodlike shape of C. minutissimum in the stratum corneum.
Corynebacterium minuti- ssimum bacterium
False-colour transmission electron
micrograph (TEM) of Corynebacterium
minutissimum, showing a single
bacterium of the Gram positive, nonsporing, aerobic species of bacilli (rodshaped bacteria). The
Corynebacterium genus includes an
important human pathogen, C.
diphtheriae the causative agent of
diphtheria; other species cause
suppurative (pus forming) diseases of
animals. An assortment of nonpathogenic species, known as
diptheroid bacilli, occur as normal flora
of human skin, upper respiratory tract,
external ears and conjunctivae
(mucous membranes of eye & inner
eyelid). Magnification: X 26,500 at
Scheme of hair microscopy
ORS: outer root sheath, CP: companion cell, IRS: inner root sheath, He
henle’s layer, Huxley layer, Ci: cuticle of IRS, Ch: cuticle of hair shaft, CO
cortex of hair shaft, Me medulla, DP dermal papilla Pattern of antibodies
against protein are shown
The human keratin family comprises 54 members, 28 type I & 26 type II. Out of the 28
type I keratin , 17 are epithelial & II are hair keratins . Similarly the 26 type I members
comprises 2O epithelial & 6 hair keratins. Out of 26 hair specific keratins only 5 have , at
present ( Schweizer,J. Experimental cell research 313 ,page 2O1O: 2OO7) been
associated with inherited hair disease
Int. J. Trichology 5: 12, 23O13
Trichomycosis axillaris is a benign, relatively common superficial bacterial infection of the axillary hair shafts and to a lesser extent, pubic
hair (trichomycosis pubis).. It is caused by the overgrowth of several species of the gram-positive diphtheroid Corynebacterium (mostly
Corynebacterium tenuis). Trichomycosis is a misleading term because the infection is not caused by a fungus as the name may imply.
The source of the organism is the skin, where Corynebacteria are plentiful.
Corynebacterium prefers moist areas of the body thus mainly affects hair shafts in sweat gland-bearing areas, such as the armpits and
the pubic area.
Superficial infection results in 1- to 2-mm adherent yellow, black or red granular nodules or concretions that surround and stick to each
hair shaft, making it appear beaded or thicker. The concretions consist of tightly packed bacteria and are most common on the central
portion of axillary hair.
The different color may be attributable to the species of Corynebacterium or to the changes in chemical environment of these organisms)
The insoluble cement substance elaborated by the bacteria adheres to the hair shaft and, occasionally, invades and destroys cuticular
and cortical keratin. The hair shaft may become brittle and thus, more easily broken, but this is rare.
Yellow concretions are the most common, whilst red and black are seen most often in tropical climates (the black the rarest). Sweat may
be coloured according to the colour of the concretions and therefore clothing can be the same color. The underlying skin usually is
normal. It occurs in both temperate and tropical climates: it is a trivial disease of worldwide occurrence. It is not limited by race or sex:
nevertheless it appears to be more common in men than women but this is because many women shave their axillary hair. It can affect
any age group from puberty through adulthood.
all that is noticed are sweaty, smelly armpits. Dermatologists are searched for the malodorous sweat and hyperhidrosis of the underarm
The treatment consists of daily cleansing with soap and water and application of benzoyl peroxide (gel or wash formulations). Topical
antibiotic preparations such as clindamycin or erythromycin are occasionally required to eliminate the infection. "Drying" powders may
assist treatment. But the fastest method to get rid of the problem is to clip or to shave the affected hairs. Once treated, it may recur if
preventive measures are not taken: the area has to be kept clean (with antibacterial soap) and dry. Regular use of antiperspirants (such
as anhydrous aluminium chloride) provide an effective means of prevention by reducing sweating.
Shaving or trimming axillary hair usually is beneficial.
Int. J. Trichology 5:L 12, 2O13
Initial trichomycosis pubis (var. flava)
Int. J. Trichology 5:L 12, 2O13
Trichomycosis, a more correct term would
be trichobacteriosis or bacterial
trichonodosis is a superficial infection,
primarily of the axillary hair, which can
exhibit three different clinical presentations:
The most common clinical variant is
trichomycosis flava (yellow), while rubra
(red) and nigra (black) variants occur much
less frequently. From the earliest reported
cases of trichomycosis, the causative agent
was classified as C. tenuis. In light of the
new taxonomic position of the genus
Corynebacterium, however, that particular
species is no longer considered, and thus,
the majority of the reports are left as
Corynebacterium sp. However, some
studies have shown that the causative
agent belongs to the so-called group 2 (LD2)
(also referred to as the CDC-G/LD group),
that it corresponds to the C. flavescens
species, and that it is related to the flava
Yellow-fluorescence of trichomycosis
pubic' hairs (Wood light)
Int. J. Trichology 5: 12, 2O13
Trichomycosis infection begins
when the causative agent comes
in contact with the hair shaft, and
the bacteria adhere to the surface,
or the cuticle, of the hair, using a
cement-like substance, the
chemical composition of which is
not yet known, that is insoluble in
water as well as in the other
principal solvents (i.e., acetone,
ethanol). Electron microscopy
studies have clearly shown that
the microorganism does not
penetrate to the medulla's cortex
of the hair; instead, it only adheres
strongly to the surface of the hair
and develops slowly until it forms
concretions around the hair shaft.
Culture of Corynebacterium sp., in chocolate-blood agar plate
Int. J. Trichology 5: 123, 2O13
An. Bras. Dermat.87 nO. 2, 2Oi2
axillaris or trichomycosis palmellina
belongs to the group of cutaneous
corynebacteriosis as well as
erythrasma and pitted keratolysis.
It is mostly caused by Coryne
bacterium tenuis and is clinically
characterized by yellowish, reddish or
blackish sticky concretions
surrounding the hair shaft of the
axillary or pubic region.
Hyperhidrosis and improper hygiene
are the main predisposing factors.
Despite its symptomless condition,
treatment may be based on cleansing
methods. Sometimes topical antibiotics
(erythromycin 2% or clyndamicin 1%)
or benzoyl peroxide may be required.
The differential diagnosis includes
white piedra, black piedra and hair
Case of Trichomycosis Axillaris and Erythrasma
J. drugs Dermat. 1O: no.12, 2O11