Indian Journal of Paediatric Dermatology

CASE REPORT
Year
: 2017  |  Volume : 18  |  Issue : 4  |  Page : 314--316

Craters of the moon: A marker for disease severity in alopecia areata?


Subrata S Malakar, Purva R Mehta, Surit S Malakar 
 Department of Dermatology, Rita Skin Foundation, Kolkata, West Bengal, India

Correspondence Address:
Purva R Mehta
15, Lovely Rose Apartments, Juhu Road, Juhu, Mumbai - 400 049, Maharashtra
India

Abstract

In cases of severe alopecia areata in children, on close trichoscopic examination, we observed that the alopecic patch was closely packed with yellow dots of various sizes. In normal subjects, sebaceous glands of the scalp secrete sebum, but the sebaceous glands are attached to the hair follicle; hence, the sebaceous material remains attached to the hair follicle as it grows. However, in patients of alopecia areata, the sebum secreted by the sebaceous glands directly opens out onto the scalp surface as the alopecic patch is devoid of hair follicle to form a yellow dot. As it is secreted directly to the scalp surface, the sebum forms a depression on the surface of the scalp. The overview of these yellow dots is akin to the “craters of the moon.” We present a case series of severe alopecia areata wherein extensive yellow dots on trichoscopy resembled the “craters of the moon” and propose the term “craters of the moon” for yellow dots in severe alopecia areata.



How to cite this article:
Malakar SS, Mehta PR, Malakar SS. Craters of the moon: A marker for disease severity in alopecia areata?.Indian J Paediatr Dermatol 2017;18:314-316


How to cite this URL:
Malakar SS, Mehta PR, Malakar SS. Craters of the moon: A marker for disease severity in alopecia areata?. Indian J Paediatr Dermatol [serial online] 2017 [cited 2019 Jul 21 ];18:314-316
Available from: http://www.ijpd.in/text.asp?2017/18/4/314/215799


Full Text



 Introduction



Extensive yellow dots are seen in cases of severe alopecia areata. The appearance of these yellow dots resembles the “craters of the moon.” As extensive yellow dots correspond to disease severity in alopecia areata, we propose “craters of the moon” sign as a poor prognostic marker in alopecia areata.

 Case Report



In a severe case of alopecia areata in a child, on close trichoscopic examination, we observed that the alopecic patch was closely packed with yellow dots of various sizes. The overview of these yellow dots was akin to the “craters of the moon.” A crater on the moon is a bowl-shaped depression or cavity with a raised rim formed by the impact of a meteorite. Similarly, yellow dots in severe alopecia areata in our case, are crater like depressions formed by sebum. Hence, we propose “craters of the moon” sign for yellow dots in severe alopecia areata [Figure 1]a,[Figure 1]b,[Figure 1]c.[1]{Figure 1}

In three other consecutive cases of severe alopecia areata in children, we have observed the same trichoscopic sign “craters of the moon,” i.e., extensive yellow dots with central depressions [Figure 2], [Figure 3], [Figure 4].{Figure 2}{Figure 3}{Figure 4}

 Discussion



Yellow dots on trichoscopy are follicular openings filled with keratosebaceous material. Yellow dots are seen in various alopecias, namely, androgenetic alopecia, alopecia areata, discoid lupus erythematosus, and alopecia areata incognito.[2],[3]

Yellow dots in alopecia areata are round or polycyclic in shape, small to medium in size and appear rough on trichoscopy.[4] Yellow dots appear as yellow or yellow pink dots that may be devoid of hair or may contain miniaturised dystrophic or cadaverized hair.[5] Their relatively regular distribution in alopecia areata is characteristic in nature.[6] Yellow dots correlate with disease severity in alopecia areata. Yellow dots and short vellus hair are the most sensitive markers for the diagnosis of alopecia areata.[7]

In alopecia areata, yellow dots contain sebum predominantly; admixed with a minimal amount of keratotic material. To comprehend the formation of yellow dots it is important to understand that in normal subjects, sebaceous glands of the scalp secrete sebum, but the sebaceous glands are attached to the hair follicle; hence, the sebaceous material remains attached to the hair follicle as it grows. However, in patients of alopecia areata, the sebum secreted by the sebaceous glands directly opens out onto the scalp surface as the alopecic patch is devoid of hair follicle to form a yellow dot.[4],[5] As it is secreted directly to the scalp surface, the sebum forms a depression on the surface of the scalp. These depressions of the yellow dots on the scalp surface resemble “craters on the moon.”

Yellow dots in discoid lupus erythematosus are sparse, larger in size, dark yellow or yellow brown in color. Moreover, they are dilated follicular infundibula primarily containing keratin.[1] The hard kertain is the reason why yellow dots in discoid lupus erythematosus do not form a depression on the scalp surface and “craters of the moon” sign is not evident in these cases.

Yellow dots in androgenetic alopecia predominantly contain sebum which is excreted to the surface of the scalp by sebaceous glands through the miniaturized hair follicle.[8] The etiopathogenesis of the formation of yellow dots in androgenetic alopecia is similar to that in alopecia areata. However, yellow dots here do not form craters as the sebum is secreted onto the scalp surface albeit in the presence of a miniaturized hair follicle.

Extensive yellow dots are a marker of disease severity in alopecia areata.[7] As the “craters of the moon” sign is equivalent to extensive yellow dots, it signifies poor prognosis in alopecia areata. Further evaluation in trichoscopy is necessary to explore the presence of this sign as it not only sheds light on the formation of yellow dots but also is an indicator of the severity of the disease.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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