Dermatology Online Journal

Letter: Pili annulati – What about racial distribution?
Filipa Osório MD, Antonella Tosti MD
Dermatology Online Journal 18 (8): 10

Department of Dermatology & Cutaneous Surgery, University of Miami Leonard M. Miller School of Medicine, Miami, Florida

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Abstract

Pili annulati is a rare hair shaft abnormality and, as far as we know, there are no published data on pili annulati’s racial distribution. To our knowledge, this is the first case reported in an African-American patient.

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Pili annulati (PA) or ringed hair is a rare hair shaft abnormality, first described in 1866 by Landois et al [1]. Since then, no more than 50 cases have been reported [2]. Hair has a speckled and shiny appearance, with characteristic alternating light and dark bands. Light bands seen by the unaided eye correspond to dark bands seen by light microscopy and electron microscopy revealed them to be air-filled cavities within the cortex of the hair shaft [3]. Cortical cells, instead of containing closely packed macrofibrils, contain an inadequate amount of otherwise normal macrofibrillar material [4].

The scalp is most frequently affected but other regions have also been described. There is variable disease expression along the hair shaft and between hairs in the same patient [5], as well as a variable age of onset, from childhood to adulthood [6]. Hair growth and tensile strength are within normal limits, but hair shafts are more susceptible to weathering [5]. Most hairs present with minor surface abnormalities associated with nodes. However, more severe hair damage and breakage can occur in a minority of cases [7].

A few conditions have been previously associated with PA, including alopecia areata, blue nevi, leukonychia, melanoderma, syndactyly, and polydactylism [6]. Yet, most patients have no concomitant abnormalities of the skin or other organs and they are often unaware of the disease [2].

PA is an autosomal dominant disorder, with a variable expression, but sporadic cases have also been described. It is probably related to a single gene defect, not yet fully recognized, the locus of which has been mapped to chromosome 12p [2, 8]. Pathogenesis is thus still unclear and the proposed mechanisms include an underlying cytokeratin abnormality, a matrix formation defect, or a defect of a regulatory protein affecting the assembly of structural proteins in the extracellular matrix [2].

Hematoxilin-eosin examination of a scalp biopsy reveals no histological abnormality and immunohistochemical studies have shown the same cytokeratin distribution as normal scalp [9]. By contrast, in a study using transmission electron microscopy (TEM), scalp specimens exhibited a reduplicated lamina densa in the region of the root bulb in comparison with the single thin electron-dense band in controls [10].

As in other hair shaft disorders, dermoscopy is useful in the diagnosis of PA [10]. Alternating light and dark areas are more clearly visible than with light microscopy; white bands correspond to air-filled cavities within the cortex. Hair weathering (trichorrexis nodosa) is also easily detected.

Figure 1	Figure 2

Herein we report the case of a 49-year-old African-American female, presenting for central centrifugal cicatricial alopecia, who on trichoscopy showed alternating light and dark bands of the hair shafts, corresponding to PA (Figure 1). Trichorrexis nodosa was also found (Figure 2). The patient was unaware of personal or family history of hair shaft abnormalities.

This is, to our knowledge, the first case of PA reported in an African-American patient. As far as we know, there are no published data on PA’s racial distribution and we believe further investigation is needed on this subject.

References

1. Landois L. Das plötzliche Ergrauen der Haupthaare. Arch Pathol Anat Physiol. 1866;35;575-599.

2. Giehl KA, Rogers MA, Radivojkov M, Tosti A, de Berker DA, Weinlich G, Schmuth M, Ruzicka T, Eckstein GN. Pili annulati: refinement of the locus on chromosome 12q24.33 to a 2.9-Mb interval and candidate gene analysis. Br J Dermatol. 2009 Mar;160;527-533. [PubMed]

3. Price VH, Thomas RS, Jones FT. Pili annulati. Optical and electron microscopic studies. Arch Dermatol. 1968 Dec;98;640-647. [PubMed]

4. Rogers M. Hair shaft abnormalities: Part II. Australas J Dermatol. 1996 Feb;37;1-11. [PubMed]

5. Giehl KA, Ferguson DJ, Dawber RP, Pittelkow MR, Foehles J, de Berker DA. Update on detection, morphology and fragility in pili annulati in three kindreds. J Eur Acad Dermatol Venereol. 2004 Nov;18;654-658. [PubMed]

6. Green J, Sinclair RD, de Berker D. Disappearance of pili annulati following an episode of alopecia areata. Clin Exp Dermatol. 2002 Sep;27;458-460. [PubMed]

7. Feldmann KA, Dawber RP, Pittelkow MR, Ferguson DJ. Newly described weathering pattern in pili annulati hair shafts: a scanning electron microscopic study. J Am Acad Dermatol. 2001 Oct;45;625-627. [PubMed]

8. Green J, Fitzpatrick E, de Berker D, Forrest SM, Sinclair RD. A gene for pili annulati maps to the telomeric region of chromosome 12q. J Invest Dermatol. 2004 Dec;123;1070-1072. [PubMed]

9. Giehl KA, Dean D, Dawber RP, Leigh I, de Berker DA, Wojnarowska F. Cytokeratin expression in pili annulati hair follicles. Clin Exp Dermatol. 2005 Jul;30;426-428. [PubMed]

10. Wallace MP, de Berker DA. Hair diagnoses and signs: the use of dermatoscopy. Clin Exp Dermatol. 2010 Jan;35;41-46. [PubMed]

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