ARTICLE
Auteur(s) :, Joong Sun Lee, You Chan Kim, Hee Young
Kang*
Department of Dermatology, Ajou University School of Medicine, 5
Wonchon-Dong, Yeongtong-Gu, Suwon 443-721, Korea (South)
accepté le 31 Août 2004
Pili multigemini is an unusual developmental defect of the hair
follicles. This condition refers to multiple hair shafts arising
from multiple divided matrices and papillae through a single pilary
canal; each hair has its own inner root sheath and the hairs are
surrounded by a common outer root sheath [1]. Pili multigemini was
first described by Flemming (1883), who found a triplet hair in the
beard skin. Multigeminate hairs have invariably been found in the
beard of an adult and the scalp of children [2]. We found three
cases of extensive pili multigemini involving the entire back of
healthy males.
Case reports
Patient 1
A 27-year-old man visited for a skin lesion on the back. His
friends found this lesion incidentally in the swimming pool. He had
no subjective symptoms related with it and was otherwise healthy.
The physical examination showed that there was a giant patch
consisting of irregular and coarse thicker hairs over the entire
back ( (figure
1A) ). Epilation did not require any considerable force and
was not painful. The direct microscopic examination of one hair
follicle showed that it consisted of more than twenty shafts, which
had rough surfaces and brush-like bulbs (( figure 2 )). The
histological examination of transverse sections revealed that
complicated follicular structures formed as many as 23 to even 36
hair shafts which were enclosed in the common outer root sheath (
(figure 1A) ).
There was eosinophilic material between the hair shafts and around
the hair shaft. It suggested that each hair had its own inner root
sheath. This was better visible in the section stained with Giemsa
solution ( (figure
3) ). There was dark material between the hair shafts and
around each shaft, which is Huxley’s layer stained deep blue.
Patient 2
A 60-year-old man who presented with generalized pruritus (( figure 1 )B). The
physician accidentally found the pili multigemini over the back
during the physical examination. The gross appearance of hair
shafts and the histopathologic examination were similar with those
of patient 1.
Patient 3
A 25-year-old man who presented with a stinging and itching
sensation, on his whole body without skin lesions for about two
years ( (figure
1C) ). The physical examination exposed pili multigemini
over half of the back which was two to three times thicker than
that of others, and folliculitis-like papules, macules are seen.
Discussion
The name ‘pili multigemini’ is used to define a kinetic papilla
that splits at the upper end from a single to a multiple-tipped one
during the anagen phase, producing eight or more different-sized
hair shafts with separate cuticles and consequently the hair shaft
does not fuse again [3]. The name ‘pili gemini’ is used when the
dermal papilla splits into a double-tipped one and should be
differentiated from pili bifurcati in which each branch is covered
with its own cuticle. We showed that lots of hairs (23 or more)
were surrounded by each cuticle and had one common outer root
sheath, which was consistent with the diagnosis of pili
multigemini. Trichostasis spinulosa, hyperkeratotic follicular
papules, are characterized by the retention of numerous vellus
hairs surrounded by a keratinous sheath in a dilated follicle, and
can be easily differentiated from our case with clinical and
histopathologic findings [4, 5].
The exact origin or mechanism of pili multigemini is still
unknown. It was suggested that a subdivided papilla produced
divided hairs, or multiple hairs may be due to the partial merging
of several papillae, or that the reactivation of silent embryonic
epithelial germs result in multigeminate hairs [1, 6]. Mehregan et
al. [7] observed the regrowth of multigeminate follicles after the
forced extraction of the hair shafts from one side of the chin.
Thus they suggested that a fixed follicular malformation with the
determining factor might reside within the area of the dermal
papillae.
Pili multigemini may be localized, most commonly in the beard
area of adults [2, 5, 8]. Our cases differ from other reported
cases in that they occur over a large area, especially over the
back. We think this nevoid multigeminate hair patch over the back
would be a commonly recognizable condition with careful
examination. In fact, in our patients the nevoid multiple hairs had
no specific symptoms, and the lesion site is the back, as a result
all cases were found by chance.
In conclusion, we report three cases of pili multigemini
involving the entire back. Pili multigemini may occur on the back
as well as the beard or the scalp and we suggest this nevoid is
pili multigemini over the back.
References
1 Cambiaghi S, Barbareschi M, Cambiaghi G,
et al. Scanning electron microscopy in the diagnosis of pili
multigemini. Acta Derm Venereol 1995; 75: 170-1.
2 Price VH. Structural anomalies of the hair shaft. Pili
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disease. Heiderlberg: Springer-Verlag, 1990: 414-5.
3 Camacho FM, Happle R, Tosti A, Whiting D.
The different faces of pili bifurcate. A review. Eur J Dermatol
2000; 10: 337-40.
4 Strobos MA, Jonkman MF. Trichostasis spinulosa:
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5 Manuskiatti W, Tantikun N. Treatment of trichostasis
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6 Pinkus H. Multiple hairs (Flemming-Giovannini). Report of
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anomalies of the pilary complex. J Invest Dermatol 1951; 17:
291-301.
7 Mehregan AH, Thompson WS. Pili multigemini. Report
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Dermatol 1979; 100: 315-22.
8 Whiting DA. Hair shaft defects. Pili multigemini and pili
bifurcati. In: Olsen EA, ed. Disorders of hair growth.
Diagnosis and treatment. New York: McGraw-Hill, 1994: 118.
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