Rare diseases · Sign or symptom

Hyperparakeratosis

HP:0040009

What it means

Histological term to illustrate the combined presence of parakeratosis and hyperkeratosis. Abnormal keratinization of the epidermal stratum corneum (horny layer) with increased keratin formation and preservation of the nuclei in the superficial cells.

Rare diseases that can present with this2

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: Parahyperkeratosis · Parakeratotic hyperkeratosis

Hyperparakeratosis

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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.