Rare diseases · Sign or symptom

Hypomelanotic macule

HP:0009719

What it means

Hypomelanotic macules ("ash leaf spots") are white or lighter patches of skin that may appear anywhere on the body and are caused by a lack of melanin. White ash leaf-shaped macules are considered to be characteristic of tuberous sclerosis.

While hypopigmentation is a general term that refers to any form of decreased or absent skin pigmentation, hypomelanosis more specifically refers to a reduction of epidermal melanin.

Rare diseases that can present with this3

The range is how often this sign appears among people diagnosed with each disease — it is not a probability of having any of them. Many of these signs also occur in common, non-rare conditions. A sign on this page is a conversation to have with a clinician, not a conclusion.

Part of the broader category

Also called: Hypomelanotic macules

Hypomelanotic macule

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This page uses the Human Phenotype Ontology (2026-06-23) — Human Phenotype Ontology Consortium, hpo.jax.org. Disease associations from Orphanet (INSERM), CC BY 4.0. Content is educational and is not medical advice.