Clinical Dermatology Review

LETTER TO EDITOR
Year
: 2020  |  Volume : 4  |  Issue : 1  |  Page : 65--66

Unmasking the casts: The true nature of pseudonits


M Sneha, AS Savitha, Nagesh Tumkur Subbarao 
 Department of Dermatology, Venereology and Leprosy, Sapthagiri Institute of Medical Sciences and Research Centre, Bengaluru, Karnataka, India

Correspondence Address:
M Sneha
Department of Dermatology, Venereology and Leprosy, Sapthagiri Institute of Medical Sciences and Research Centre, No. 15, Chikkasandra, Hesaragatta Main Road, Bengaluru - 560 090, Karnataka
India




How to cite this article:
Sneha M, Savitha A S, Subbarao NT. Unmasking the casts: The true nature of pseudonits.Clin Dermatol Rev 2020;4:65-66


How to cite this URL:
Sneha M, Savitha A S, Subbarao NT. Unmasking the casts: The true nature of pseudonits. Clin Dermatol Rev [serial online] 2020 [cited 2021 May 13 ];4:65-66
Available from: https://www.cdriadvlkn.org/text.asp?2020/4/1/65/275238


Full Text



Sir,

A 23-year-old female presented to the outpatient dermatology department of a tertiary care hospital with complaints of small, white structures on the hair strands which she had accidentally noticed few months ago while combing her hair. There were no associated symptoms. The patient did not give a history of any other lesions on the scalp or elsewhere on the body. Other family members had no such complaints. The patient reported that there was no noticeable change in these white structures even after head bath. She used to tie her hair loosely in a band and did not give a history of usage of any hair gel, hair spray, or hair serum and had not subjected her hair to any kind of cosmetic hair procedures.

On examination, we noticed that multiple, shiny, white, easily movable, cylindrical concretions measuring around 2–8 mm were present on numerous hair shafts. They were localized to the right parieto-occipital region. There was sparing of proximal 1–2 cm of the hair and the distal part. Terminal hair in the other regions remained unaffected. The scalp examination was unremarkable. The clinical photograph of the hair casts involving scalp has been presented in [Figure 1]. Dermatoscopy revealed cylindrical structures ensheathing the hair shafts and has been presented in [Figure 2] and [Figure 3] is the dermatoscopic photograph showing proximal 1–2 cm of the hair shaft being spared by the hair casts. KOH mount was negative for fungal elements. Based on the clinical and dermatoscopic findings, we established the diagnosis of pseudonits. The patient was advised to use tretinoin 0.025% cream. She was lost to follow-up.{Figure 1}{Figure 2}{Figure 3}

Hair casts or pseudonits as they are commonly called are slender, discrete, shiny, white-to-yellowish, nonadherent, cylindrical, freely movable concretions that ensheath the hair shafts.[1],[2],[3] Being freely movable, they easily slide through the hair on traction.[3] Although the condition is not unusual, there seems to be a lacuna in establishing the diagnosis, which may be attributed to the scarcity of literature on the same.[2],[3] Further, false diagnosis leads to inadequate treatment, the outcome of which is anxious patient and physician.[3]

Kligman, in the year 1957 for the first time, used the term hair casts in his article “parakeratotic comedones of scalp.”[4] The normal outward growth of the hair carries the root sheaths of hair along with it.[5] For reasons yet to be determined, there is a failure in the desquamation of some of the root sheaths, and they remain encircled to hair shaft after their exit from the hair follicle, which eventually break off and form hair casts.[5]

Hair casts are classified into nonparakeratotic peripilar (idiopathic) casts and parakeratotic (secondary) casts.[1] The disorders resulting in the scaling of the scalp such as psoriasis, seborrheic dermatitis, and pityriasis amiantacea form secondary hair casts.[1] Other causes for secondary hair casts include infective scalp conditions such as pediculosis capitis, trichorrhexis nodosa, white piedra, and trichomycosis.[1]

Hair casts are commonly seen in females who tightly plate their hair for prolonged periods.[6] Hence, they are seen in females who style their hair in braids, twists, dreadlocks, braids, and weave with extensions and in those who use overnight rollers.[5] The above-mentioned hairstyles cause excessive traction, leading to local scalp ischemia and inflammation, which is known to promote the development of hair casts.[6] Hair casts induced by traction encircle single hair shaft and the parakeratosis is not prominent.[6]

The case presented here had the involvement of only scalp hair. However, hair casts are known to involve beard, chest, axillary, and pubic hair.[1] The fact that hair casts easily slide along the shafts helps in differentiating them from other disorders of the scalp such as pediculosis capitis, piedra, trichomycosis, trichonodosis, and trichorrhexis nodosa.[1],[2],[5],[7],[8] Hair casts often get misdiagnosed as pediculosis capitis; however, the latter is symptomatic.[1],[2]

Taïeb et al.[9] established the effectiveness of 0.025% tretinoin lotion in the treatment of hair casts.[9] Hair casts tend to recur after discontinuation of the medication.[1] Although the condition is benign, if the diagnosis is not established properly, it can cause unnecessary anxiety in both the patient and the treating physician.[1],[3],[5],[8] Hair casts are infrequently reported; physicians should consider pseudonits as a differential diagnosis since they mimic many common scalp disorders.

Declaration of patient consent

The informed consent was obtained for participation in the study and publication of data and images for research and educational purposes.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

References

1Lokhande AJ, Lokhande AJ, Sutaria A. Adult onset hair casts: Nits which do not itch! Int J Trichology 2017;9:70-2.
2França K, Villa RT, Silva IR, de Carvalho CA, Bedin V. Hair casts or pseudonits. Int J Trichol 2011;3:121-2.
3Minelli L, Gon AD, Sales NC. Casts: Three cases report and literature review. An Bras Dermatol 2006;81:159-62.
4Klingman AM. Hair casts; parakeratotic comedones of the scalp. AMA Arch Derm 1957;75:509-11.
5Scott MJ Jr., Roenigk HH Jr. Hair casts classification, staining characteristicsand differential diagnosis. J Am Acad Dermatol 1983;8:27-32.
6Tosti A, Miteva M, Torres F, Vincenzi C, Romanelli P. Hair casts are a dermoscopic clue for the diagnosis of traction alopecia. Br J Dermatol 2010;163:1353-5.
7Ganguly S, Kuruvila S. Hair casts. Indian J Dermatol Venereol Leprol 2014;80:97.
8Scott MJ Jr., Roenigk HH Jr. Hair casts: Classification, staining characteristics, and differential diagnosis. J Am Acad Dermatol 1983;8:27-32.
9Taïeb A, Surlève-Bazeille JE, Maleville J. Hair casts. A clinical and morphologic study. Arch Dermatol 1985;121:1009-13.