|
Pili
annulati
The
name pili annulati refers to hair fiber with rings - sometimes
called ringed hair. In pili annulati the hair fiber has alternating
light
and dark bands along its length like zebra stripes. Usually this
hair defect is most obvious in people with blond hair as dark hair
obscures the light and dark band pattern.
Pili annulati is the result of abnormal keratinization in the
hair shaft. The cortex is not a solid structure. It contains spaces
or vacuoles between the cells in the center of the cortex. These
spaces are filled with air and make excellent minute mirrors to
reflect light. Along the length of a hair fiber there are clusters
of these spaces at regular intervals that reflect the light while
neighboring sections of the fiber with fewer spaces reflect much
less light. Consequently the hair looks like it has stripes. The
bands can be seen regardless of what direction the source of light
is coming from. The hair fiber is overall still very strong although
the cuticle can be disrupted and folded. Hair breaking can occur
in these fibers across the bands where the hair shaft spaces are
present.
Pili annulati most frequently develops in children and can be
present from birth. Some individuals show a family inheritance pattern
that is autosomal dominant. Other cases are isolated and sporadic
with no apparent overt genetic component. Pili annulati can sometimes
be found in people with alopecia areata or woolly hair. There is
no known treatment but the banding pattern is quite appealing.
Pili
annulati references
- Moffitt
DL, Lear JT, de Berker DA, Peachey RD. Pili annulati coincident
with alopecia areata. Pediatr Dermatol. 1998 Jul-Aug;15(4):271-3.
- Meyvisch
K, Song M, Dourov N. Review and new case reports on scanning electron
microscopy of pili annulati, Monilethrix and Trichothiodystrophy.
Scanning Microsc. 1992 Jun;6(2):537-41.
- Brambilla
L, Boneschi V, Chiappino G, Bruognolo L, Sala F, Tadini GL. [Structural
and ultrastructural study of an isolated case of pili annulati].
G Ital Dermatol Venereol. 1990 Sep;125(9):383-7.
- Lalevic-Vasic
B, Polic D. [Pili annulati. A scanning electron microscopy study].
Ann Dermatol Venereol. 1988;115(4):433-40.
- Ito M,
Hashimoto K, Sakamoto F, Sato Y, Voorhees JJ. Pathogenesis of
pili annulati. Arch Dermatol Res. 1988;280(5):308-18.
- Gummer
CL, Dawber RP. Pili annulati: electron histochemical studies on
affected hairs. Br J Dermatol. 1981 Sep;105(3):303-9.
- Amichai B, Grunwald MH, Halevy S. Hair
abnormality present since childhood. Pili annulati. Arch Dermatol.
1996 May;132(5):575, 578.
- Smith SR, Kirkpatrick RC, Kerr JH, Mezebich
D. Alopecia areata in a patient with pili annulati. J Am Acad
Dermatol. 1995 May;32(5 Pt 1):816-8.
- Dini G, Casigliani R, Rindi L, Grappone
C, Melli MC, Lotti T. Pili annulati. Optical and scanning electron
microscopic studies. Int J Dermatol. 1988 May;27(4):256-7.
- Tomidei M, Bundino S, Puiatti P, Torre
C, Strani GF. [Pili annulati: study of a family with ultrastructural
research]. G Ital Dermatol Venereol. 1987 Sep;122(9):427-30.
- Price VH, Thomas RS, Jones FT. Pili annulati.
Optical and electron microscopic studies. Arch Dermatol. 1968
Dec;98(6):640-7.
|
