Congenital systematized basaloid follicular hamartoma with microphthalmia and hemimegalencephaly.

The lines of Blaschko are a cutaneous pattern of mosaicism present in a variety of skin disorders. Developmental abnormalities affecting other tissues derived from the embryonic ectoderm and mesoderm are sometimes associated. Here, we describe a 5-year-old boy with basaloid follicular hamartoma affecting the left side of the body in linear multiple bands, following Blaschko lines. Lesions were predominantly hypopigmented macules and streaks, but among these, we could observe brownish atrophic patches and brown papules. Furthermore, ipsilateral hemimegaloencephaly and microphthalmia were present. These findings suggest a neurocutaneous condition recently described by Happle and Tinschert. Its nosologic classification will be discussed.