Hypomelanotic macules are otherwise known as ash-leaf spots due to their resemblance to Sorbus aucuparia, or mountain-ash, leaves. These macules have a strong association with tuberous sclerosis and are often multiple and present in the vast majority of individuals with the condition (up to 97% 1). As such the presence of more than three hypomelanotic macules prompts further investigation.
Histologically, melanocytes are distributed normally within the stratum basale of the epidermis but contain a reduced level of melanin 2.
Important differentials to consider include:
- nevus anaemicus: mediated by vasoconstriction
- achromic nevus: a form of congenital mosaicism, where some melanocytes have a reduced ability to generate melanin
- 1. Jóźwiak S, Schwartz RA, Janniger CK, Michałowicz R, Chmielik J. Skin lesions in children with tuberous sclerosis complex: their prevalence, natural course, and diagnostic significance. Int J Dermatol. 1998 Dec;37(12):911-7.
- 2. Klaus J. Busam. Dermatopathology. Elsevier Health Sciences, 1 Jan 2010.