Review classification of palmoplantar keratosis and children

[allenbaron]

Is your request related to a specific disease?

'palmoplantar keratosis' (DOID:3390) is more often referred to as 'palmoplantar keratoderma' (current synonym) or PPK.

Describe the proposed change(s)

Currently, the children of this disease are organized into the following subgroups: epidermolytic, nonepidermolytic, striata, punctate, and the singular mal de Meleda.

It seems that modern classification of PPKs is based primarily on the morphology of the keratoderma, including 3-4 types: diffuse, focal, striate or punctate (^1 and Table 1[^2]; an example of 3 groups in the Abstract[^3]).

• DO only partially matches this primary grouping, since it immediately groups by epidermolytic/nonepidermolytic and has no "diffuse" or "focal" groupings).
• NCI and MeSH have less organized/up-to-date groupings, which probably should not be relied upon.
• SNOMED has significantly more complex groupings that are less clear cut.
• Orphanet](https://www.orpha.net/en/disease/classification/sibling/158293?orphaCode=79357&plus=1&entry=530838&mode=name) follows the diffuse/focal/punctate groupings (3 groups) seen in these 2 publications.

Should we revise the DO classification to include "diffuse" and "focal" groups? This would primarily alter the arrangement of diseases under 'nonepidermolytic palmoplantar keratoderma' (DOID:0050428l; NEPPK).

Note that it appears some PPKs may be missing from DO, e.g. KRT1-related NEPPK, Huriez syndrome, Palmoplantar keratoderma Nagashima type, etc.

[^2]: Dev T, Mahajan VK, Sethuraman G. Hereditary Palmoplantar Keratoderma: A Practical Approach to the Diagnosis. Indian Dermatol Online J. 2019 Jul-Aug;10(4):365-379. doi: 10.4103/idoj.IDOJ_367_18. PMID: 31334055; PMCID: PMC6615398. [^3]: Thomas BR, O'Toole EA. Diagnosis and Management of Inherited Palmoplantar Keratodermas. Acta Derm Venereol. 2020 Mar 25;100(7):adv00094. doi: 10.2340/00015555-3430. PMID: 32147745; PMCID: PMC9128927.

[allenbaron]

OMIM includes 3 groups for classification:

PPK has been classified into diffuse, focal, and punctate forms according to the pattern of hyperkeratosis on the palms and soles (Lucker et al., 1994).[^1]

[^1]: See Classification of Palmoplantar Keratoderma section of EPPK1, https://www.omim.org/entry/144200.

[allenbaron]

@lschriml & @sbello,, should we revise the DO classification to include "diffuse" and "focal" groups, and drop the ''nonepidermolytic palmoplantar keratoderma' (DOID:0050428l; NEPPK) grouping?

A few additional diseases to add:

• PALMOPLANTAR KERATODERMA, NAGASHIMA TYPE - https://omim.org/entry/615598 - a diffuse type
• KERATOSIS, FOCAL PALMOPLANTAR AND GINGIVAL - https://www.omim.org/entry/148730 - a focal type
• PALMOPLANTAR KERATODERMA AND WOOLLY HAIR - https://www.omim.org/entry/616099 - a striate type

[allenbaron]

We could keep the NEPPK grouping, under a "diffuse" grouping. It would only include the new 'KRT1-related NEPPK' and 'Bothnian type palmoplantar keratoderma'.

I think 'Naxos disease' should probably be reclassified since the skin phenotypes can be variable[^1].

[^1]: Description, https://omim.org/entry/601214.