Trichoscopy is a helpful tool in the diagnosis and management of hair and scalp disorders.1 Dirty dots have been described as a normal trichoscopic finding in the scalps of 10 of 19 healthy children (53%) between 5 months and 14 years of age.2 None of the children had a preceding hair or scalp disorder. The dirty dots presented as clumped and haphazardly arrayed particulate debris and loose fibers of various colors. They are absent in adults2 and, to our knowledge, have not been reported in people of other ages.
We retrospectively and independently reviewed the trichoscopic images of 107 elderly women (aged 65-86 years) seen in an outpatient dermatology clinic from October 1, 2014, to May 30, 2015. The project was approved by the University of Miami Institutional Review Board. The images of 65 patients were obtained at ×20, ×40, and ×70 magnification by using an interface solution of 70% isopropyl alcohol for the FotoFinder videodermatoscope (FotoFinder Systems), and the rest were obtained at ×20 magnification without the use of an interface solution via a cross-polarized handheld device—the Handyscope (FotoFinder Systems)—attached to an iPhone 4S (Apple Inc). Data analysis was conducted from July 1 to August 30, 2015.
All patients were postmenopausal women with Fitzpatrick skin type I to III diagnosed with chronic telogen effluvium or androgenetic alopecia. Dirty dots were detected in the scalp of 34 patients (31.8%). The dots appeared as brown, yellow, and black clumps of less than 0.1 to 0.5 mm distributed haphazardly in the scalp (Figure 1) and were better appreciated with the cross-polarized dermatoscope. None of the patients had features for seborrheic dermatitis. No difference was found between the amount of the dirty dots and the patients’ age, skin type, or diagnosis.
Dirty dots can be encountered as a normal finding on trichoscopy in at least one-third of elderly women and are better visualized with the cross-polarized dermatoscope (dry dermoscopy). The dots are less numerous than in children, most likely owing to differences in the grooming habits of both groups.
While dirty dots were present in prepubertal children, they were absent in infants younger than 9 months and in children older than 10 years.2 This finding suggested that the dirty dots result from the inability of the scalp to repel particulate debris from exogenous environmental sources due to a relative decrease in the sebaceous glands. In fact, the particles were easily cleared after shampooing.
The normal pattern of sebaceous gland activity in humans is cyclic. In the newborn, the sebaceous gland is fully developed and involutes in the following months due to the decrease of maternal androgens to become a mantle, that is, an immature sebaceous gland presenting as cords of epithelial cells emanating from both sides of the hair follicle at its upper level.3 On horizontal sections, the mantle appears as a skirt encircling the hair follicle (as it is a 3-dimensional structure), and on vertical sections it appears as 2 cords of epithelial cells, like a cloak. During puberty and adulthood, the sebaceous glands are well developed and undergo involution during menopause and andropause when the androgen level decreases and again acquires the mantle appearance in old age (Figure 2). Another supporting fact for the involution of the sebaceous glands is the absence of seborrheic dermatitis in our patients, similar to that seen in the original report.2
In conclusion, the physician should distinguish dirty dots from 2 common trichoscopic findings. The first is black dots, which are found in individuals with several disorders, including but not limited to alopecia areata, trichotillomania, chemotherapy-induced alopecia, tinea capitis, and scarring alopecia.4 Black dots correspond to remnants of hair shafts in the follicular ostia and cannot be removed mechanically. They are usually associated with other forms of broken hairs. The second trichoscopic finding is hair dye; if hair is improperly washed, dye can deposit on the scalp and may even penetrate the follicular ostia. While hair dye deposits can be confused with dirty dots, they are usually more diffuse and cannot be removed with shampooing.5
Corresponding Author: Mariya Miteva, MD, Department of Dermatology and Cutaneous Surgery, University of Miami Miller School of Medicine, 1600 NW 10th Ave, Rosenstiel Science Medical Building, Room 2023A, Miami, FL 33136 (email@example.com).
Accepted for Publication: November 10, 2015.
Published Online: January 20, 2016. doi:10.1001/jamadermatol.2015.5545.
Author Contributions: Drs Miteva and Tosti had full access to all the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis.
Study concept and design: Miteva.
Acquisition, analysis, or interpretation of data: All authors.
Drafting of the manuscript: Miteva, Lima.
Critical revision of the manuscript for important intellectual content: Miteva, Tosti.
Administrative, technical, or material support: Miteva, Lima.
Study supervision: Miteva, Tosti.
Conflict of Interest Disclosures: None reported.
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et al. ‘Black dots’ seen under trichoscopy are not specific for alopecia areata. Clin Exp Dermatol
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