A school-aged girl presented to the dermatology clinic with a 6-year history of hair loss and short hair. Her scalp hair was relatively normal in terms of density and length at birth. Since the age of 1 year, the girl had begun to have frequent hair loss without pulling. Her mother also found that her hair grew to approximately the same maximum length down to the upper neck without trimming. On clinical examination, diffuse, short, sparse, lanugolike, black hair over the scalp was found (Figure, A and B). The surface of the scalp was smooth without inflammatory changes or focal alopecic patches. No involvement of eyebrows, eyelashes, nails, teeth, or body hair was found. Her intellectual performance was normal at presentation and no developmental delay had ever been noted. She denied experiencing a stressful event recently, and no habitual pulling of hair was observed by her family. Family history regarding hair loss was unremarkable.
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D. Hypotrichosis simplex of the scalp
Histopathologic evaluation showed increased telogen hairs and decreased anagen-to-telogen hair ratio in the horizontal section. Only a scant perifollicular infiltrate of histiocytes and lymphocytes was found. Ancillary genetic testing was conducted due to suspicion of familial hypotrichosis after clinicopathological correlation. Whole exome genome testing revealed 2 heterozygous variants in the lanosterol synthase gene (c.812T>C and c.1025T>G). A diagnosis of hypotrichosis simplex of the scalp (OMIM 618275) was made. No effective treatment is available for hypotrichosis simplex and further genetic testing was recommended for her parents.
Hypotrichosis simplex is a group of monogenic isolated alopecias that begins in childhood and progresses with age without spontaneous resolution.1 It was first described by Toribio and colleagues2 in 1974 and features familial hair loss limited to the scalp in the early school years, progressing to almost total alopecia in the patient’s mid-20s. Most of the patients have disease onset at birth or in the first decade of life with an inability to grow long hair. Diffuse hair loss of the scalp without hair shaft abnormalities or other ectodermal involvement, such as nails and teeth, is characteristic; extensive involvement to other body areas has also been reported, including eyebrows, eyelashes, or body hair. The discrepancy between clinical phenotypes may be associated with different underlying genetic variants.
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CME Disclosure Statement: Unless noted, all individuals in control of content reported no relevant financial relationships. If applicable, all relevant financial relationships have been mitigated.
Corresponding Author: Chih-Chiang Chen, MD, PhD, Department of Dermatology, Taipei Veterans General Hospital, No. 201, Sec 2, Shipai Road, Beitou District, Taipei, Taiwan 11217, China (email@example.com).
Published Online: November 23, 2022. doi:10.1001/jamadermatol.2022.5034
Conflict of Interest Disclosures: Dr Chen reported grants from the National Science and Technology Council during the conduct of the study. No other disclosures were reported.
Additional Contributions: We thank the patient for granting permission to publish this information.
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