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 30 year-old Brazilian woman of skin phototype IV and pregnant for 35 weeks sought medical care for presenting hyperchromic lines on both legs for 5 weeks. Hyperchromia in the axillae and groin, which had appeared earlier in the pregnancy, were concurrent complaints. There were no associated symptoms. She had a history of gestational diabetes, which was been treated with NPH insulin since the 26th week of pregnancy and was under control. It was her second pregnancy, and she denied similar alterations in the previous one. Hormonal disorders had been previously discarded by an endocrinologist. Physical examination revealed demarcation lines from the perineum to the posteromedial portion of the thighs extending to the ankles through the popliteal fossae, bilaterally and symmetrically, in the interface between a hyperchromic lateral portion and a lighter medial portion ( and ). Hyperchromic axillae and prominent linea alba were also seen.