A Case Report
Di-Qing Luo, MMS, Yu-Hua Liang, MMS, Xi-Qing Li, PhD, Yu-Kun Zhao, MMS,
Fang Wang, MMS, and Rashmi Sarkar, MD
Abstract: Cutaneous pili migrans and creeping eruption caused
by parasitic diseases may present as a moving linear lesion in skin.
The former, caused by a hair shaft or fragment embedded in the
superﬁcial skin or middle dermis, is a rare condition characterized
by creeping eruption with a black line observed at the advancing end.
In exceptionally rare instance, the hair grows inside the skin and
burrows in the uppermost dermis, such a condition has been called
We report a 30-year-old Chinese man, who was accustomed to
pull or extrude the beard hairs, with 1-year history of slowly
extending black linear eruption on his right chin. Cutaneous exam-
ination revealed a 4-cm long black linear lesion beneath the skin
associated with edematous erythema around and folliculitis on both
ends of the lesion. After treatment with topical mupirocin ointment,
the erythema and folliculitis improved and 2 hairs of the beard with
hair follicles were pulled out from the skin. Two weeks later,
another similar black line about 1 cm in length in the skin presented
on the prior lesional area, which was pulled out by a shallow incision
of the skin and was also demonstrated as a beard hair with hair
The patient was diagnosed as ‘‘ingrowing hair’’ with multiple
recurrences. The lesions recovered after the beard hairs were pulled
out. No recurrence occurred in a year of follow-up.
We suggest that ‘‘ingrowing hair’’ is better than ‘‘ingrown hair’’
to describe such a condition. Pulling out the involved hair and
correcting the bad practice are its optimal management strategies.
Cutaneous pili migrans is a rare condition characterized by a
hair fragment or hair shaft moving in the shallow epidermis
or dermis, forming an eruption resembling larva migrans.
to date, no more than 30 cases of cutaneous pili migrans have
been reported since its first description by Yaffee
in 1957, and
it has Asian predilection.
However, we considered that
cutaneous pili migrans has been underestimated, because even
the present corresponding author and the colleagues had met 4
cases since 2009. Among them, 2 had been previously
and another 2 whom were diagnosed recently
had not been reported yet. Interestingly, there is an exception-
ally rare condition previously called ‘‘ingrown hair’’ mimick-
ing the presentations of cutaneous pili migrans, in which the
causative factor is a hair growing inside the skin and burrowing
in the uppermost dermis rather than a hair shaft moving inside.
To our knowledge, only 4 cases published in Japanese literature
have been reported (Table 1),
and none in English literature
have been described. Herein, we report a case and suggest to
rename it as ‘‘ingrowing hair.’’
A 30-year-old Chinese man without any relevant medical
histories was referred because of 1-year history of slowly
extending black linear eruption on his right chin, which gradu-
ally protracted toward the back of neck without any associ-
ations. No treatments were administered. A week prior to
presentation, the lesion presented with painful erythema around
it. The patient usually shaved his beard by blade, and was
accustomed to pull or extrude the beard hairs when he had spare
time. He denied acne history on his neck. No other family
members were similarly affected. Cutaneous examination
showed that a 4.3-cm-long black linear eruption beneath the
skin located on the right chin, associated with edematous
erythema around it and 2 inflammatory papules on both ends
of the lesion (Figure 1A). After 1-week treatment of topical
mupirocin ointment, the edematous erythema and papules
improved excellently, and a hair shaft with its distal end
protruding out of the skin was observed which was pulled
out with ease (Figure 1B and C). The hair, measured 4 cm in
length, was demonstrated a hair shaft with follicles under
microscope (Figure 1D). Meanwhile, another hair, about
0.3 cm far from the follicle of the priorly pulled beard hair,
was also found which showed a short section protruding out of
the skin near the root. By pulling the hair near the root with
forceps, a 2.2-cm-long, slippery, straight, black hair was easily
removed from the skin (Figure 1C, the white arrow). Then the
patient continued with topical mupirocin ointment. Two weeks
later, the patient returned and the erythema improved markedly.
However, a new black linear lesion about 1 cm in length
appeared in the skin in the region of prior erythema
(Figure 1E). After a shallow incision of the skin, a 1-cm-long
Editor: Ismael Maatouk.
Received: September 15, 2015; revised: April 3, 2016; accepted: April 19,
From the Department of Dermatology (D-QL, Y-KZ, FW), The Eastern
Hospital of The First Afﬁliated Hospital, Sun Yat-sen University,
Guangzhou; Department of Dermatology (Y-HL), The Fifth People’s
Hospital of Foshan, Foshan; Department of Dermatology (X-QL), Sun Yat-
sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China; and
Department of Dermatology (RS), Maulana Azad Medical College and
LNJP Hospital, New Delhi, India.
Correspondence: Di-Qing Luo, Department of Dermatology, The Eastern
Hospital of The First Afﬁliated Hospital, 183 Huangpu Rd E., Sun
Yat-sen University, Guangzhou 510700, P. R. China
(e-mail: email@example.com; firstname.lastname@example.org).
Written informed consent was obtained from the patient for publication of
this case report and any accompanying images.
D-QL, Y-HL, and X-QL are equal contributors.
The authors have no conﬂicts of interest to disclose.
Copyright #2016 Wolters Kluwer Health, Inc. All rights reserved.
This is an open access article distributed under the Creative Commons
Attribution-NoDerivatives License 4.0, which allows for redistribution,
commercial and non-commercial, as long as it is passed along unchanged
and in whole, with credit to the author.
CLINICAL CASE REPORT
Medicine Volume 95, Number 19, May 2016 www.md-journal.com |1
hair with follicles was extracted from the epidermal burrow
(Figure 1F). The patient was given topical mupirocin ointment
for a week, and was asked to stop pulling or extruding the beard
hairs. Three months later, only mild erythema left behind
(Figure 1G). No relapse occurred during 1 year of following-up.
Based on the entities that the black lines were beard hairs
with follicles extending gradually rather than hair shafts moving
alone, we considered that the present conditions resulted from
the hairs growing inside the skin, and we diagnosed them as
‘‘ingrown hair’’ rather than ‘‘cutaneous pili migrans.’’ Con-
sidering the hairs had been growing inside the skin until they
were pulled out, we prefer to term the present instance as
‘‘ingrowing hair’’ rather than ‘‘ingrown hair,’’ which may
be a more appropriate way to describe the disease, and can
be distinguished from the condition in pseudofolliculitis barbae
in which the hair also grows inside the skin and causes pseu-
Although the exact mechanisms for ingrowing hair remain
unknown, we considered that the actions of pulling or extruding
the beard might play important roles for the present patient,
because the actions might result in possibility of localized
inflammation and edema around the follicle, and/or changing
the growing direction of the beard hair, that made the hair grow
inside the skin possible. While the hair was growing slowly
inside the skin, the black lesion was extending gradually, and
the length of lesion may be equal to the length of the ingrowing
hair (excluding the follicle section). But when the hair follicle is
deceased, the hair might move inside the skin as cutaneous pili
migans does. When the hair is growing inside the skin, it may
also cause physical stimulation causing possible erythema
around. In the present case, a hair shaft extruded out of the
skin after the inflammation improved, we thought that the
erythema may be a possibly inflammatory reaction stimulated
by the hair, and the hair was excluded from the skin as a foreign
body finally. Of course, we cannot exclude the possibility that
localized infection played a role in some extent for the
Based on the literature, only 5 cases, including the present
patient, have been reported and all were men with an age range
of 30- to 58-year old (Table 1).
The involved locations
included the neck,
and chin. Three occurred on the
neck. The results suggested that ingrowing hair always occurs
on the area where the beard hairs are distributed, and beard hairs
may be the causative hair. All the prior cases were from Japan
and the present case is from China. To our knowledge, no
similar cases were described in other areas, mimicking
cutaneous pili migrans with Asian predominance.
reasons of Asian predominance for cutaneous pili migrans
are because that Asian hair, especially the Japanese, has larger
diameter with circular geometry, and is harder and straighter
than African or Caucasian hair,
which may make the Asian hair
extend and grow inside the skin easier than that of other
We speculated that the mechanisms for the
Asians’ predilection of ingrowing hair are the same as they
are in cutaneous pili migrans. However, we lack the data of any
possible difference of the beard hairs between Asia and
The differential diagnoses included cutaneous pili
migrans, interdigital pilonidal sinus, creeping eruption caused
by parasitic diseases, and pseudofolliculitis barbae. Cutaneous
pili migrans is caused by hair shaft or fragment, or the pubic
hair, and always without hair follicles, showing a painful linear
lesion with a moving black line at the advancing end.
length of the black line is stable while the lesional length
extended gradually. A hair can be pulled out by a shallow
incision of the skin.
But we speculated that, when the follicle
is deceased, ‘‘ingrowing hair’’ may became ‘‘cutaneous pili
migrans.’’ Interdigital pilonidal sinus, commonly occurring in
the barber, is caused by the naked hair shaft or fragment
penetrating the follicle and entering the dermis without extend-
ing the lesion.
The creeping eruption caused by parasitic
disease is always caused by nematode larva, in rare condition,
subcutaneous migration of a fly’s maggot (migratory myiasis),
an adult nematode (Loa loa, Dracunculus medinensis), a tre-
matode larva (F. gigantica), or Sarcoptes scabiei may be the
Its lesion is mobile and tracks sinu-
ously, commonly associated with severe itching without pre-
sence of black line.
A parasite is always found at the advancing
end of the lesion. Pseudofolliculitis barbae is an inflammatory
disorder that occurs most frequently in men with a dense and
curly beard, presenting as the curly hair tending to curl into the
skin instead of straight out the follicle.
caused by shaving or depilation may be the triggering factor.
But in rare instance, the hairs come out of and again re-enter the
skin causing solid papules with bent hairs inside.
clinical features, it is not difficult to make a correct diagnosis for
As ingrowing hair is caused by a hair growing inside the
skin, extracting the hair and correcting the bad habit may be its
optimal management strategies. The present case is notable
because of multiple ingrowing hairs and recurrent lesions. To
the best of our knowledge, no similar case had been reported
Ingrowing hair is a rare cutaneous disease caused by hair
growing inside the skin and characterized by slowly extending
black linear lesion beneath the skin, the length of the lesion is
TABLE 1. Summaries of Reported Cases of Ingrowing Hair
Case No Sex Age, y
Length of the
Length of the
Hair, cm Reference
1 Male 42 Right cheek 6 4.5 3
2 Male 34 Neck 2.5 2.5 3
3 Male 58 Right frontal neck 5 5 3
4 Male 52 Right frontal neck 3 3 3
5 Male 30 Right chin Multiple (4.0/2.2/1.0) Multiple (4.0/2.2/1.0) Present
Luo et al Medicine Volume 95, Number 19, May 2016
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FIGURE 1. The presentations of ingrowing hair. A 4.3-cm-long black linear lesion beneath the skin located on the right chin associated
with edematous erythema around and 2 inﬂammatory papules on both ends of the lesion (A). The folliculitis improved excellently after
treatment with topical mupirocin ointment for a week, and a hair shaft with its distal end protruding out of the skin presented on the lesion
(B). A hair (grasped by the forceps) (C) with hair follicle (D, the white arrow; the inset showing a closer view of the hair, 100) is easy pulled
out; the second hair shaft (C, the white arrow) with its follicle in skin is pulled out from the skin. A new black linear lesion about 1 cm in
length appeared in the skin in the region of prior erythema 2 weeks later after pulling out of the prior beards (E), showing hair shaft with
hair follicle (F). Mild erythema left behind in 3 months of follow-up (G).
Medicine Volume 95, Number 19, May 2016 Ingrowing Hair
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always equal to the length of the hair except that inflammatory
reaction occurs. It may involve the cheek, chin, and neck, and
may be multiple or recurrent. Pulling out the hair and correcting
the bad habit are its optimal treatments.
The authors thank the patient participating in the
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Luo et al Medicine Volume 95, Number 19, May 2016
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