Pili annulati

Pili annulati
Pili annulati
Other names	Ringed hair disease
Specialty	Medical genetics

Pili annulati (also known as "ringed hair")^[1] is a genetic trait in which the hair seems 'banded' by alternating segments of light and dark color when seen in reflected light.^[1]^[2]^: 767^[3]^: 640^[4]

Pili annulati manifests during infancy or at birth. The clinical manifestation varies. Usually, the hair appears shiny and banded. Pili annulati usually just affects the scalp but can be present in other areas.

Pili annulati may be sporadic or inherited in an autosomal dominant fashion. Pili annulati can be diagnosed based on light microscopy or trichoscopy. Treatment is not needed.

Pili pseudoannulati is an anomaly of human hair that mimics pili annulati; however, the two differ in that the light bands of pili annulati are caused by internal effects, whereas the bright segments of pili pseudoannulati are caused by reflection and refraction of light by flattened, twisted surfaces of hair.^[2]^: 767

Signs and symptoms

Pili annulati might show up during infancy or at birth.^[5] Within the same patient, the clinical manifestation may vary at different parts of the scalp or even within the same afflicted hair.^[6]^[7]^[8]

The clinical examination typically finds the hair to be shiny and banded, with an occasional odd shimmering texture or even frizzy look.^[9] As the hair develops, the amount of white bands tends to diffuse.^[10]

Higher hair fragility is not usually linked to pili annulati.^[10] A small percentage of cases show significant trichorrhexis-nodosa-like hair fracturing and breakage together with enhanced sensitivity at the light band level.^[11]^[12]

Although pili annulati is mostly restricted to the hair on the scalp, it can also affect hair in the pubic, axillary, and beard areas.^[9]^[7]

Causes

Pili annulati are inherited in an autosomal dominant pattern that exhibits varied expression. There has also been sporadic cases reported.^[10] There is documentation of a case of pili annulati linked to a mutation in RECQL4, which causes Rothmund-Thomson syndrome.^[6]

Diagnosis

A distinctive look with alternating bright and dark stripes in the hair shaft is revealed by light microscopy. In light microscopy, the dark bands correlate to white bands in reflected light, in trichoscopy, and macroscopically. A normal medulla with clusters of sporadic, air-filled cavities within the cortex of the hair shafts is visible under transmission electron microscopy of the affected hairs.^[10] A "cobblestoned" and fluted cuticle is shown via scanning electron microscopy.^[5]^[13]

Similar to other illnesses of the hair shaft, trichoscopy is a quick and easy way for practitioners to diagnose pili annulati without having to remove hairs.^[10]

Treatment

Since pili annulati is a benign illness for which individuals never seek medical attention, treatment is frequently not necessary.^[10]

References

^ ^a ^b Rapini, Ronald P.; Bolognia, Jean L.; Jorizzo, Joseph L. (2007). Dermatology: 2-Volume Set. St. Louis: Mosby. ISBN 978-1-4160-2999-1.
^ ^a ^b James, William; Berger, Timothy; Elston, Dirk (2005). Andrews' Diseases of the Skin: Clinical Dermatology. (10th ed.). Saunders. ISBN 0-7216-2921-0.
^ Freedberg, et al. (2003). Fitzpatrick's Dermatology in General Medicine. (6th ed.). McGraw-Hill. ISBN 0-07-138076-0.
^ "OMIM Entry - % 180600 - RINGED HAIR".
^ ^a ^b Amichai, B. (1996-05-01). "Hair abnormality present since childhood. Pili annulati". Archives of Dermatology. 132 (5). American Medical Association (AMA): 575. doi:10.1001/archderm.132.5.575. ISSN 0003-987X. PMID 8624159.
^ ^a ^b Rudnicka, Lidia; Olszewska, Małgorzata; Waśkiel, Anna; Rakowska, Adriana (2018). "Trichoscopy in Hair Shaft Disorders". Dermatologic Clinics. 36 (4). Elsevier BV: 421–430. doi:10.1016/j.det.2018.05.009. ISSN 0733-8635. PMID 30201151.
^ ^a ^b Teysseire, S.; Weiler, L.; Thomas, L.; Dalle, S. (2017). "Pili Annulati". Annales de Dermatologie et de Vénéréologie (in French). 144 (5). Elsevier BV: 399–400. doi:10.1016/j.annder.2016.12.003. ISSN 0151-9638. PMID 28109542.
^ Laniosz, Valerie; Podjasek, Joshua O.; Camilleri, Michael J.; Hand, Jennifer L. (2013). "Pili Annulati Masquerading As Hypotrichosis". Pediatric Dermatology. 30 (4). Wiley: 510–511. doi:10.1111/pde.12111. ISSN 0736-8046. PMID 23819454.
^ ^a ^b Theodosiou, G; Hamnerius, N; Svensson, A (2018). "Banded Scalp Hair with an Unusual Glistening Appearance in a Teenager: A Quiz". Acta Dermato Venereologica. 98 (4). Medical Journals Sweden AB: 473–474. doi:10.2340/00015555-2891. ISSN 0001-5555.
^ ^a ^b ^c ^d ^e ^f Chabchoub, Ines; Souissi, Asmahane (2023-06-26). "Pili Annulati". StatPearls Publishing. PMID 31082025. Retrieved 2024-03-23.
^ Osório, Filipa; Tosti, Antonella (2012-08-01). "Pili annulati – What about racial distribution?". Dermatology Online Journal. 18 (8). doi:10.5070/D323H0G5QZ. ISSN 1087-2108.
^ Nam, Chan Hee; Park, Minkee; Choi, Mi Soo; Hong, Seung Phil; Kim, Myung Hwa; Park, Byung Cheol (2017). "Pili Annulati with Multiple Fragile Hairs". Annals of Dermatology. 29 (2). Korean Dermatological Association and The Korean Society for Investigative Dermatology: 254–256. doi:10.5021/ad.2017.29.2.254. ISSN 1013-9087. PMC 5383763. PMID 28392665.
^ Moffitt, DL; Lear, JT; de Berker, DA; Peachey, RD (1998). "Pili annulati coincident with alopecia areata". Pediatric Dermatology. 15 (4). Wiley: 271–273. doi:10.1046/j.1525-1470.1998.1998015271.x. ISSN 0736-8046. PMID 9720689.