Hereditary Hypotrichosis Simplex of the Scalp

Abstract

Hereditary hypotrichosis simplex of the scalp is a genetic disorder, characterized by sparse or absent scalp hair without structural defects, in the absence of other ectodermal or systemic abnormalities. Structural hair defects may be presented with a genetic disorder affecting hair growth or part of a congenital syndrome or may indicate underlying metabolic disorders, or may be associated with other diseases. We describe a 26-years-old Persian girl suffering from hypotrichosis simplex of the scalp with trichorrhexis nodosa who had no ectodermal defects and systemic disease.

Introduction

What was known?

Hereditary hypotrichosis simplex of the scalp (HSS) is a rare autosomal dominant genotrichosis characterized by a hair defect confined to the scalp in the absence of other ectodermal or systemic abnormalities.

Hereditary hypotrichosis simplex of the scalp (HSS) is a rare autosomal dominant genotrichosis characterized by a hair defect confined to the scalp in the absence of other ectodermal or systemic abnormalities.[1] We describe this entity in a 26-year-old girl.

Case Report

A 26-year-old girl referred to our dermatology clinic because of sparse and short hair. She had normal hair at birth, but hair loss began when she was four months old. She had short hairs of varying length, its length, never exceeds 7 cm. On physical examination, she had normal physical and mental development with no neurological impairment. Diffuse thinning of the scalp hair was seen. In addition, her scalp hair was sparse and fragile with no signs of cicatricial alopecia [Figure 1].

Figure 1.

Sparse and fragile hair with no sign of cicatricial alopecia

Eyebrows and eyelashes, nails, dental, eyes and sweat glands were normal. There was no other ectodermal dysplasia. Her pull test was positive; it easily shed with slight pulling. She had family history of the same disease in six cousins of both gender. The parents were nonconsanguineous. The following investigation: blood count, erythrocyte sedimentation rate, liver, thyroid and renal function tests, serum electrolytes, urinalysis, blood glucose, the glucose tolerance test, Hb A1C, copper, zinc, and ferritin. Proteins, quantitative immunoglobulins, and amino acid were normal. Trichogram of the patient's hair show multiple abnormalities: Distorted hair bulbs, ruffling and fraying of hair cortex with fracturing of hair shaft, resembling trichorrhexis nodosa [Figure 2].

Figure 2.

Distorted hair bulbs, ruffling and fraying of hair cortex with fracturing of hair shaft

A scalp biopsy show marked decrease number of hair follicles; most of them are in anagen phase, accompanied by mild chronic predominantly lymphocytic perifollicular infiltration, consistent with hypotrichosis simplex. Cicatricial alopecia dose not found [Figure 3].

Figure 3.

Marked decrease number of hair follicles, most of them are in anagen phase, accompanied by mild chronic predominantly lymphocytic perifollicular infiltration, consistent with hypotrichosis simplex

Discussion

Hereditary hypotrichosis simplex of the scalp (HSS) is a rare autosomal dominant genotrichosis characterized by a hair defect confined to the scalp in the absence of other ectodermal or systemic abnormalities.[1] Usually, patients with the (HSS) present with normal hair at birth and in the first years of life. They experience a progressive, gradual loss of hair that is limited to the scalp, beginning at the middle of the first decade and leading to almost complete loss of scalp hair by the third decade. A few sparse, fine, short scalp's hairs remain in some individuals. The body hair, beard, eyebrows, axillary hair, teeth, and nails are normally developed.[2] Mental development and intelligence are normal. This non-syndromic alopecia affects males and females equally. Scalp skin biopsy revealed a decreased number of follicles, especially in the telogen phase, with no specific pattern and no structural changes.[2,3] Before, only five families with this variant of hypotrichosis have been present.[3] Structural hair defects may be presented with a genetic disorder affecting hair growth or part of a congenital syndrome or may indicate underlying metabolic disorders, or may be associated with other diseases. Abnormalities of the hair shaft are varied and often confusing and can be congenital or acquired. They do require accurate recognition, which can be helpful in the diagnosis and management of a hair disorder, or in the detection of underlying disease.[4] Trichorrhexis nodosa is a common shaft defect affecting scalp hair, in which there is a distinctive response to injury. The hair is fragile and on examination regularly, spaced pale ‘node-like’ swellings may be observed. It may affect normal hair following excessive or repeated trauma, or may occur after minimal trauma if there is an inherent defect in keratin synthesis causing abnormally brittle hair.[5,6] Blume-Peytavi U, et al. suggested the triad of hypotrichosis, structural hair-shaft defects (dysplastic and broken hair shafts as seen in pili torti, trichorrhexis nodosa and pseudomonilethrix), and abnormal amino-acid composition (hypercysteine hair), associated with glucosuria without diabetes, may represent a new genetic syndrome due to an enzyme defect or deficiency.[7] In 2004, a novel hidrotic ectodermal dysplasia (Hypotrichosis, trichorrhexis nodosa and nail dystrophy) in a 3-year-old girl was reported.[8] We reported a 26-year-old Iranian girl affected by HSS associated with trichorrhexis nodosa with history of the same disease in six members of her family. Investigation suggested mutations in lipase H (LIPH) were responsible for autosomal recessive hypotrichosis simplex with woolly hair in three families.[9]

Conclusion

Human hair as a key phenotypic marker can lead us to the underlying metabolic or genetic syndromes.[7] The finding of hypotrichosis simplex of the scalp, associated with structural hair-shaft defects in seven adults of one family who were otherwise healthy, in the latest generation may represent a new genetic syndrome.

What is new?

The finding of hypotrichosis simplex of the scalp, associated with structural hair-shaft defects in seven adults of one family who were otherwise healthy, in the latest generation may represent a new genetic syndrome.