Dermoscopy for the Diagnosis of Creeping Hair Caused by Ingrowing Hair: A Case Report

Abstract

Creeping hair is a rare condition characterized by creeping eruption with a black line at the advancing end, mimicking cutaneous larva migrans. The condition is also referred to as cutaneous pili migrans, migrating hair, and embedded hair. A total of 52 cases have been reported since 1957 and most cases were published in English. Herein, we report a case in which creeping hair occurred in the iliac region and review the literature from 1957 to February 2021. A 35-year-old Chinese female presented with a black moving linear eruption that had migrated from the lower abdomen to the iliac region without causing any symptoms during a 3-year period. Cutaneous examination showed a 6.5-cm-long black linear lesion beneath the skin that was revealed to be a hair shaft. After removal of the hair, the eruption diminished and no recurrence occurred in 3 months of follow-up. The creeping hair that had migrated with its lower end forward was confirmed by observation under dematoscopy and light microscopy. A review of the literature revealed that creeping hair occurs most frequently in young and middle-aged patients and the reported cases are mainly from Asia. The top locations involve the foot. The causative hair includes head hair, beard, pubic hair, body hair, and one case of dog hair. A close-up examination and dermoscopic inspection are helpful for the diagnosis of creeping hair.

INTRODUCTION

Creeping eruption is a linear or serpiginous cutaneous track that is slightly elevated, erythematous, and mobile¹. The most representative example of creeping disease is cutaneous larva migrans. In rare cases, hair-induced creeping eruption in the skin can mimic cutaneous larva migrans. This condition was first reported by Yaffee in 1957², and is described in the literature as imbedded hair, bristle migrans, pili cuniculati (burrowing hair), pseudolarva migrans, migrating hair, moving hair, intradermal creeping of pubic hair, hair fragments in the skin, cutaneous pili eruption, creeping hair, ingrown hair, and ingrowing hair²,³,⁴,⁵. The lesion is characterized by a creeping eruption with a black-line-like hair at the advancing end with or without erythema³,⁴. In most cases, the causative hair shaft fragment migrating in the shallow epidermis is visible from the skin surface. In such a condition, dermatoscopy can be used to observe the lesion and aid in diagnosis⁶,⁷. However, in certain cases, the causative hair is burrowed in the deep dermis and the lesion appears as only raised erythema; thus, diagnosis may require a skin biopsy⁸. Herein, we report a case of creeping hair diagnosed by dermoscopy and review the relevant literature.

CASE REPORT

A 35-year-old Chinese female noted an asymptomatic black threadlike line on her left lower abdomen 3 years ago. Three days prior to presentation, she found that the lesion had advanced to her iliac crest and the eruption was very superficial. Her attempts to remove it by herself had failed.

On physical examination, there was a fine, very superficial, black line about 6.5 cm in length observed through the skin surface. There were no signs of inflammation surrounding the lesion, although there was a small area of broken epidermis made by the patient herself (Fig. 1A). The black line was clearly visible under dermoscopy (Fig. 2A) and a Z-shaped angle was seen in the middle of the lesion without any signs of inflammation (Fig. 2B).

Fig. 1. (A) An evident, fine, very superficial, black line was clearly visible through the skin surface, without any sign of inflammation on the surrounding skin. (B) A dark hair was extracted from its epidermal bed measuring 2.0 cm in length at the broken epidermis made by the patient herself located near the advancing end. (C) A dark twisting pubic hair was extracted from its epidermal bed measuring 3.5 cm in length at the Z-shaped angle position.

Fig. 2. (A) A black line was clearly visible under the dermoscopy with a superficial erosion of the advancing end of the lesion (original magnification×50). (B) A Z-shaped angle was shown in the middle of the lesion without any signs of inflammation under the dermoscopy (original magnification×50). (C) A white and transparent membrane adherent to the surface of hair shaft and the hair fragment end was observed by dermoscopy (original magnification×100). (D) The hair root end was the advancing end of the lesion and it showed a bulbous shape observed by dermoscopy (original magnification×100).

We made a small incision in the region of the broken epidermis and used a pair of small forceps to remove a 2.0-cm-long black linear object (Fig. 1B). It was difficult to remove the linear object from the epidermal bed and it broke off from the main body of the lesion. Histopathological examination revealed a hair structure. Dermoscopy revealed that the black linear object was a naked hair shaft (Fig. 2C). The patient easily extracted the advancing end at home using a pair of tweezers while she waited for her pathological result. One week later, she brought us the advancing end that was about 1.0 cm in length, and dermoscopy revealed that it was a hair root (Fig. 2D). Hence, a shallow slit was made at the position of the Z-shaped angle, and the remnant hair was easily extracted (Fig. 1C). The hair was a twisting hair that resembled pubic hair and was about 3.5 cm in length. After removal of the hair, the eruption diminished and there has been no recurrence during 3 months of follow-up.

DISCUSSION

To our knowledge, a total of 52 cases of hair-induced eruption have been reported since 1957²,³,⁴,⁵,⁶,⁷,⁸,⁹,¹⁰,¹¹,¹²,¹³,¹⁴,¹⁵,¹⁶,¹⁷. The characteristics of these cases, including ours, are summarized in Table 1. The lesion locations include the ankle, sole, toe, forefoot, palm, leg, suprapubic region, umbilical region, iliac crest, buttock, abdomen, breast, waist, cheek, neck, jaw, mandibular angle, and scalp. However, the foot and toe are the most common sites of occurrence. The disease tends to occur in young and middle-aged patients, and the male to female ratio is 2.26:1. The period from the onset of the eruption to the first clinical visit ranges from 12 hours to 10 years. Thirty-eight of the 52 reported cases of hair-induced creeping eruption were found and reported in Asia. The large number of cases reported in Asia may be because Asian hair has maximal tensile strength and the largest cross-sectional area compared with other ethnic groups¹⁸. The causative hair includes head hair, beard, pubic hair, body hair, and one case of dog hair. The causative hair length is 0.5 to 8.0 cm. Notably, our patient had a long asymptomatic period between the discovery of the lesion and the time at which she consulted a dermatologist. This is the first report of creeping hair occurring in the iliac region of a Chinese patient.

Table 1. Case reports about hair-induced creeping eruption.

No.	Year	Sex	Age	Duration	Location	Material	Length of hair (cm)	Author	Language	Country
1	1957	F	19 yr	2 wk	Ankle	Hair	4.0	Yaffee HS	English	USA
2	1961	F	15 mon	2 day	Right sole	Bristle	2.0	Schamberg, I. L	English	USA
3	1962	F	32 yr	NF	Left toe	Leg hair	N	Francesco R	English	USA
4	1975	M	2 yr	N	Right foot	Hair	0.9	Lehmuskallio EA	English	Finland
5	1979	NF	NF	NF	NF	Hair	3.0	Itani ZS	German	Germany
6	1985	M	31 yr	NF	Groin to right buttock	Hair	4.5	Miyauchi et al.	Japanese	Japan
7	1986	M	43 yr	NF	Pubis to iliac crest	Hair	3.0	Takino et al.	Japanese	Japan
8	1990	M	39 yr	NF	Near the navel	Hair	3.0	Ohta et al.	Japanese	Japan
9	1990	M	42 yr	NF	Right cheek	Hair	5.5	Takino et al.	Japanese	Japan
10	1993	F	32 yr	NF	Iliac crest	Pubic hair	N	Ueda et al.	Japanese	Japan
11	1994	F	21 yr	NF	Pubis to left abdomen	Hair	1.3	Takagi et al.	Japanese	Japan
12	1994	F	31 yr	NF	Left breast	Hair	1.5	Oka et al.	Japanese	Japan
13	1997	M	58 yr	NF	Right frontal neck	Hair	5.0	Saito et al.	Japanese	Japan
14	2001	M	2 yr	NF	Right outer sole	Hair	N	Shibuya	Japanese	Japan
15	2001	F	32 yr	NF	Groin to right waist	Hair	1.3	Nakayamaeta	Japanese	Japan
16	2001	M	37 yr	N	Jaw	Hair	7.0	Thai KE	English	India
17	2002	F	31 yr	NF	Groin to left back	Hair	3.0	Nakagawa et al.	Japanese	Japan
18	2003	M	52 yr	NF	Right frontal neck	Hair	3.0	Nakano et al.	English	Japan
19	2004	F	3 yr	2 day	Right sole	Hair	2.0	Neri et al.	English	Italy
20	2006	M	55 yr	1 wk	Groin to left back	Pubic hair	4.5	Sakai et al.	English	Japan
21	2009	M	39 yr	2 wk	Neck	Hair	6.0	Ishida et al.	English	Japan
22	2009	M	28 yr	5 day	Left sole	Hair	3.5	Luo et al.	French	China
23	2010	F	38 yr	30 day	Left foot	Hair	NC	Luo et al.	English	China
24	2010	M	3 yr	1 day	Bilateral sole	Hair	2.2/3.5	Kim et al.	English	Korea
25	2011	M	62 yr	20 day	Left foot	Hair	2.5	Arakawa et al.	English	Japan
26	2011	M	41 yr	1.5 yr	Neck	Hair	6.2	Bihua et al.	Chinese	China
27	2012	F	2 yr	10 day	Left foot	Hair	N	Yilmas et al.	English	Turkey
28	2012	M	6 mo	N	Left leg	Hair	2.5	Xie et al.	English	China
29	2013	F	20 mo	5 day	Right sole	Hair	NF	Marchal, A	French	France
30	2013	M	28 yr	10 day	Right chin	Hair	N	Yuling et al.	Chinese	China
31	2014	M	54 yr	3 day	Foot	Dog hair	NF	Vanhaecke C	English	Cameroon
32	2014	M	46 yr	3 wk	Neck	Beard	7.0	Kim et al.	English	Korea
33	2015	M	31 yr	1 mo	Neck	Beard	7.0	Jang et al.	English	Korea
34	2016	F	30 yr	3 mo	Left breast	Hair	N	Khare et al.	English	India
35	2016	M	42 yr	2 mo	Right toe	Hair	N	Khare et al.	English	India
36	2016	M	N	1 mo	Scalp	Body hair	N	Rahul et al.	English	India
37	2016	M	30 yr	1 yr	Right chin	Beard	2.2	Luo et al.	English	China
38	2016	NF	NF	NF	NF	Hair	N	Kim et al.	Korean	Korea
39	2017	M	2 yr	NF	Sole	Hair	NF	Youn et al.	Korean	Korea
40	2017	M	14 mo	NF	Foot	Hair	NF	lopez et al.	Spanish	Mexico
41	2017	F	56 yr	NF	Right palm	Hair	0.5	Couty et al.	French	France
42	2018	M	2 yr	N	Right foot	Hair	0.5	Traniello et al.	English	Italy
43	2018	M	3 mo	N	Left sole	Hair	N	Traniello et al.	English	Italy
44	2018	NF	NF	NF	Axilla	Hair	NF	Kim et al.	Korean	Korea
45	2019	M	26 yr	N	Mandibular angle	Beard	N	Liu et al.	English	China
46	2019	M	31 yr	N	Neck	Beard	8.0	Liu et al.	English	China
47	2019	M	27 yr	1 wk	Neck	Hair	2.0	Minting et al.	Chinese	China
48	2019	M	23 yr	2 wk	Neck	Hair	3.0	Minting et al.	Chinese	China
49	2020	F	39 yr	1 wk	Neck	Hair	N	Ingkapairoj K	English	Thai
50	2020	M	4 yr	3 mo	Scalp	Hair	6.0	Ding et al.	Chinese	China
51	2021	M	34 yr	10 yr	Suprapubic region	Pubic hair	1.0~3.0	Willems A	English	Australia
52	2021	M	53 yr	1 mo	Mandibular region	Hair	N	Juan et al.	Chinese	China
53	2020	F	35 yr	3 yr	Left lower abdomen to left iliac	Pubic hair	6.5	Present case	English	China

F: female, M: male, N: not described, NF: not found because no such journals in our hands.

The term creeping hair was first used by Sakai et al.³ in 2006. In his report Sakai reviewed Japanese reports and found eight cases of migration of the hair shaft or hair fragment in the shallow skin located on the lower abdomen or pubic region, and six cases of migration toward the iliac region, creating a wavy linear eruption. There is only one previously reported case of creeping hair in the suprapubic region with the same location and migration direction as the present case³,⁷. Interestingly, two of the cases reported by Sakai were demonstrated to have creeping hair migrating with the terminal end at the advancing end. The same phenomenon was found in our case, as the advancing end of the lesion was the terminal end structure of the hair root. We consider that an ingrown hair in the pubic area curled back and grew inward and deeper after being released from the hair follicle, as the lower end of an ingrown pubic hair is naturally oriented toward the iliac region. 3 Our observations using the naked eye and dermoscopy revealed that the causative hair was twisted and unlike the head or body hair. Thus, we diagnosed the cause of the creeping hair as an ingrown pubic hair in our case.

The differential diagnoses for creeping hair include creeping eruption caused by parasitic diseases, interdigital pilonidal sinus, and pseudofolliculitis barbae. The lesion caused by parasitic disease is mobile and the tracks are sinuous, commonly associated with severe pruritus, and lacks a black line; furthermore, a parasite is always found at the advancing end of the lesion⁵. Interdigital pilonidal sinus is caused by short sharp hairs that penetrate the interdigital space of the hand; the causative hair fragment cannot be observed from the skin surface, and ultrasonography aids in the diagnosis of this disease¹⁹. Pseudofolliculitis barbae is a chronic inflammatory disorder of the follicular and perifollicular skin; the curved shape of the hair follicle enables the downward curvature and penetration of the growing hair tip into the skin, leading to pruritus and the development of papules, pustules, and post-inflammatory hyperpigmentation²⁰. It is not difficult to correctly diagnose such disorders.

In addition to a close-up examination, dermoscopy is a useful tool to distinguish between these similar disorders. The characteristic dermoscopic finding of creeping hair eruption is a straight linear black lesion. The black line is easily movable within a whitish 1-mm-wide linear eruption under the pressure of the lens¹⁰. Creeping hair can also present as a fine, very superficial, dark line that is easily movable under the pressure of the lens and surrounded by a 2- to 3-mm erythematous area¹¹. Dermoscopy enables the visualization of morphologic hair structures that are not visible to the naked eye, including the head of the hair root, and the differentiation of an unbroken hair from a hair fragment.

The treatment for creeping hair is simple. A small incision is made at one end of the black line and the hair is extracted from its epidermal bed with a pair of small forceps. In our experience, the hair is easily pulled out from the tail end of the migrating lesion. In conclusion, creeping hair is a rare condition that can be diagnosed by careful clinical observation and dermoscopic inspection.