Incontinentia pigmenti (IP) is a rare X-linked dominant multi-systemic ectodermal dysplasia usually lethal in males and presenting neonatally in females with a bullous rash along Blashko's lines (BL) followed by verrucous plaques evolving over time to hyperpigmented swirling patterns. It is further characterized by teeth abnormalities, alopecia, nail dystrophy and affects occasionally the retina and the central nervous system (CNS).

Keratoacanthoma (KA) is a common benign epithelial tumour that originates from the pilosebaceous glands. In most cases, it is characterized by rapid evolution, followed by spontaneous resolution over 4 to 6 months. KA usually presents as a solitary flesh-coloured nodule with a central keratin plug on the sun-exposed skin of elderly individuals.