Mask-Associated Trichorrhexis Nodosa — Donovan Hair Clinic
Gangal et al., 2022
The report described a 31-year-old man who presented to clinic with concerns about his facial hair. For 8 months, the beard hair was noted to be breaking, be of uneven length and have multiple ‘‘white dots’’ limited to the hairs of his beard. The man felt this was a problem localized only to the beard and hair elsewhere was normal.
Initially he was diagnosed with seborrheic dermatitis and treated with triamcinolone 0.025% lotion daily without improvement.
Examination up close in the clinic revealed white nodes on the hair shafts. The skin of the beard area was normal with no signs of erythema, scale, or other signs of redness. When hairs were examined with trichoscopy, a ‘paint brush’’ appearance could be seen. This is the appearance of hairs at the site of breakage and fragility and appears as though two paint brushes were pushed together.
The patient worked as a barber, and due to the COVID-19 pandemic, had been wearing a facial covering to work starting approximately 9 months prior to his presentation. After this diagnosis, he was advised to limit manipulation of the area and change his mask to reduce friction.
FINAL DIAGNOSIS: TRICHORRHEXIS NODOSA
The diagnosis was trichorrhexis nodosa (TN).
Trichorrhexis nodosa refers to the light microscopic appearance of a fracture with splaying out of individual cortical cells from the main hair shaft, producing an appearance suggestive of two brushes pushed together. Clinically the nodes appear at irregular intervals.
Key Learning Points form this Case
This is an interesting case as it reminds us of a number of very important teaching points.
POINT 1: What is the Differential Diagnosis of White Dots on Hairs
This was an interesting case as it reminds us of a few important things about white dots on hairs. The differential diagnosis of such white flecks included white piedra, hair casts, pediculosis, TN, trichorrhexis invaginata, and seborrheic dermatitis. in this particular case, the authors pointed out that there were no lice, nits, peripilar scale, or casts seen during trichoscopy. A bacterial swab grew normal skin flora, and hair-pull fungal culture was negative. Blood tests were normal.
POINT 2: What is the Differential Diagnosis of Trichorrhexis Nodosa?
Trichorrhexis nodosa (TN) refers to the light microscopic appearance of a fracture with splaying out of individual cortical cells from the main body of the hair shaft, producing an appearance suggestive of two brushes pushed together.
In 1852, Samuel Wilks of Guy’s Hospital first described the condition, although the term trichorrhexis nodosa was not proposed until 1876 by M. Kaposi.
There are three variants that we should all know about:
1) Primary Congenital Form of TN (also called Congenital TN)
2) Secondary TN as Part of other Genetic Syndromes
3) Acquired TN from Repeated Trauma on the Hair (as in this case)
1) Primary Congenital TN
Congenital TN is inherited in an autosomal dominant manner. The hair is said to be normal at birth and then becomes fragile in early infancy. The hair may improve in some cases with time.
2) Secondary TN Associated with Genetic Syndromes
TN can occur as part of syndromes. This differs from primary TN because there are many other medical issues present in the child. TN can be seen in argininosuccinic aciduria, citrullinemia, and trichohepatoenteric syndrome, monilethrix, trichothiodystrophy, Netherton syndrome, Menkes syndrome and biotinidase deficiency. Pili annulati has also been associated with TN.
3) Acquired TN Associated with Physical or Chemical Trauma to the Hair Shaft
The acquired form of TN is frequently to physical trauma or chemical trauma to the hair shaft during styling practices. Examples would include excessive heat or chemicals or excessive combing of hair, or excessive scratching, rubbing or itching of the scalp. Swimming in chlorinated water has been proposed as a cause.
Under this category, we would also include the poorly described “Seasonal Trichorrhexis Nodosa” whereby affected patients start developing TN each summer following repeated swimming in salt water and exposure to intense UV radiation following by trauma that comes from frequent shampooing and hair brushing. This is thought to again be caused by hair trauma.
4) Acquired TN Associated with Systemic Diseases
Less often, acquired TN may be a manifestation of malnutrition (especially iron deficiency) or an endocrinopathy (especially thyroid disease due to mucin in hair causing a weakening of hair shaft).
5) Acquired TN Associated with Medications
Medications have been associated with TN including methotrexate, TNF inhibitors, MEK inhibitors such as trametinib).
In cases fo acquired TN, it is important to exclude fungal or bacterial causes that are making the hair weaker. Cultures can therefore be helpful. Inflammatory issues within the skin and hair need to be considered as well as these too can weaken hair. Frontal fibrosing alopecia, lichen planopilaris and alopecia areata can weaken hairs and make them more susceptible to breakage.
Gangal et al. Mask-associated acquired trichorrhexis nodosa of the beard. JAAD Case Rep. 2022 Mar;21:101-102.
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