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.
We report the case of a 27-year-old healthy male who presented with an area of curlier and thinner hair than the rest of his scalp localized on the right parietal area. He referred that just at that location, his hair had been different since childhood, curlier than the rest. Physical examination revealed a plaque with shorter and curlier hair on an area of 10 cm in diameter on the right parietal area of the scalp. A decreased density of hair was observed. The skin on the patch was apparently healthy. There were not exclamation mark hairs or miniaturization of hair follicles. A hair pull test was negative []. A skin biopsy showed a mild perifollicular lymphocytic infiltrate, telangiectatic capillaries in the superficial dermis and several terminal hair follicles emerged in the same dilated follicular infundibulum. Interestingly, an excessive amount of normal apocrine glands were found in the deep reticular dermis. Counting of hair follicles was normal [Figure –]. Based on clinical appearance and histopathologic studies, a diagnosis of WHN was established.