A patient with woolly hair nevus syndrome, presented with epidermal facial nevi by the age of 12 years. Despite transient improvement with topical 1% sirolimus cream, the facial nevus grew larger. The patient was then treated with topical 1% everolimus cream resulting in a reduction in the size of the nevus. This case highlights a novel use of topical 1% everolimus cream, which previously has not been used to treat epidermal nevi.

Germline mutations in HRAS cause Costello syndrome (CS), while mosaic mutations in HRAS show a variability of phenotypes, ranging from mild features such as keratinocytic epidermal nevus (KEN), sebaceous nevus (SN), woolly hair nevus (WHN) with KEN, to severe manifestations of CS with cutis laxa. We report two individuals. The first was a 2-year-old boy with woolly hair nevus (WHN) without any other cutaneous involvement, in whom somatic HRAS mutation (c.34G>A; p.Gly12Ser) was identified in his affected scalp and hair follicle specimens. This is the first reported WHN type 1 (no cutaneous involvement) patient caused by somatic HRAS mutation. The other individual was a 12-year-old girl with CS caused by germline HRAS mutation (c.34G>A), that manifested with coarse face, palmoplantar keratoderma, deep palmar and plantar creases, hyperpigmented patches, asymmetry and deformity of lower limbs, atopic dermatitis, as well as mental retardation. Of note, a linear hyperpigmented plaque was observed in her father's lumbosacral region. Although the father refused to provide semen and skin tissue for further examination, this reminds us of possible mosaicism in parents of individuals with germline de novo HRAS mutation and underlines the importance of parental evaluation for prenatal counseling.

Woolly hair nevus is a rare entity characterized by structural anomaly, which presents as curly hair in a circumscribed area of scalp, in a nonNegroid individual. These are abnormal hairs which are short, thin, and sparse. The term "woolly hair" refers to tightly coiled hair covering the whole scalp or part of it and has a hereditary character. Trichotillomania is a chronic impulse control disorder, characterized by the repetitive pulling out of one's own hair, leading to noticeable hair loss. Here, we present the case of a 9-year-old male child with woolly hair nevus over the occipital area, which developed at the age of 3 years; later, he developed trichotillomania at the age of 5 years, adjacent to the nevus. According to the best of our knowledge, there is no case report of woolly hair nevus presenting with trichotillomania till date.