{'fraction_non_alphanumeric': 0.026022304832713755, 'fraction_numerical': 0.002973977695167286, 'mean_word_length': 5.289719626168225, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Novel postzygotic KRAS mutation in a Japanese case of epidermal nevus syndrome presenting with two distinct clinical features, keratinocytic epidermal nevi and sebaceous nevi

Dear Editor, Epidermal nevus syndrome (ENS) is a heterogeneous congenital disorder characterized by the presence of epidermal nevi associated with systemic involvement. Keratinocytic epidermal nevus (KEN) syndrome and sebaceous nevus (SN) syndrome are included in ENS which share the same postzygotic HRAS and KRAS gene mutations that are relevant for cell proliferation. A HRAS mutation can induce nevus marginatus, a combined nevus of KEN and SN, and this suggests an identical genetic background of KEN and SN. Here, we report a case of ENS exhibiting both KEN and SN characteristics caused by a novel postzygotic KRAS mutation. A 3-year-old Japanese girl presented with multiple nevoid lesions along Blaschko lines on the left side of her body that she had had since birth. The skin lesions, which were light red at the neonatal stage (Fig. 1a), had transformed into two distinct types: yellowish plaques suggesting SN on the sebaceous gland-rich craniofacial area, and brownish verrucous lesions suggesting KEN on the trunk and extremities (Fig. 1b). Histological evaluation showed papillomatosis and acanthosis with overlying laminated hyperkeratosis (Fig. 1c,d).