A 5-year-old Japanese boy presented to the dermatology department with multiple linear pigmentations on the arms and trunk. Linear brown verrucous papules on the left forearm were noticed at about 9 months after birth (Figure A), and nuchal pigment macules were recognized at 1 year old. Linear and whorled hyperpigmentation then appeared gradually on the patient's back, axilla, and chest (Figure B). There was no hyperkeratosis of the palms or soles. Woolly hair was observed locally on the scalp (Figure C). Other than the skin manifestations, the patient did not exhibit any other symptoms. Neither the patient's parents nor his sister had woolly hair or linear pigmentation. Histopathologically, a skin biopsy specimen on the axilla with linear pigmentation showed hyperkeratosis, hypermelanosis, acanthosis, and papillomatosis of the epidermis that was consistent with an epidermal nevus (Figure ). Genetic screening was conducted after obtaining written informed consent. Next-generation sequencing of the genomic DNA purified from the epidermis of the epidermal nevus enzymatically separated from the dermis using custom-targeted exome sequencing panels of the Haloplex target enrichment system. Sanger sequencing revealed an HRAS c.34G>A (p.G12S) mutation specifically in the epidermis but not in the dermis of the epidermal nevus and the blood (Figure ). Analyses of the mRNA determined the identical HRAS mutation in the hair roots of the woolly hair but not of the straight hair (Figure ). Echocardiography and abdominal ultrasound performed after genetic diagnosis showed no abnormal findings.
A 5-year-old girl child presented with abnormal patch of hair since 2 years of age. Her parents noticed a single patch of curling and coiling of hair along with altered texture over the left side of scalp. Her parents felt the patch to be unruly and unsightly and hence attempted repeated tonsuring. In spite of this, the patch of hair remained the same. Birth and development history of the child was normal. Her family members did not have similar complaints. On examination, we noticed a solitary circumscribed patch of size 6×4 cm located over the left frontoparietal region of scalp. The hair over the patch had an altered texture, was lighter in color, thinner, tightly coiled, and curled giving an unkempt appearance []. The skin over the patch was apparently normal. Examination of rest of the scalp, teeth and nails were also normal. There was no evidence of palmoplantar keratoderma and evidence of any epidermal nevus elsewhere. Ophthalmic and cardiac evaluation did not reveal any abnormality. There was no evidence of precocious puberty. Based on the above findings, we arrived at a diagnosis of localized woolly hair nevus. Hair microscopic examination showed non-specific features. Scalp biopsy revealed normal hair follicles and appendages []. Routine hemogram, serum biochemistry, electrocardiogram and echocardiogram were normal.