A few days ago, I was following an online chat with some international friends, and the following alphabet-soup conversation erupted:
American #1: Can you guys remind me what types of ichthyosis you have? I have EHK.
Briton #1: What’s that?
American #1: Epidermolytic hyperkeratosis. I think they call it bCIE in your country. Lately I’ve been hearing people say they have epidermolytic ichthyosis. I still get confused with all the technicalities.
American #2: I have Ichthyosis Bullosa of Siemens, which they now call EHK-Siemens variant, whatever that means. It makes one’s head spin trying to keep up with it all.
Australian: My son has EHK, I thought they were calling it EI, epidermolytic ichthyosis now, I prefer EHK.
Briton #2: I have nonbullous congenital ichthyosiform erythorderma.
Briton #3: I have LI – Lamellar. I keep seeing ARCI. I’m so confused.
Excuse me while I go clean up the mess caused by my head exploding. I’ll wait while you get some Tylenol, paracetamol, or acetaminophen, and it looks like some dermatologists are staking out the medicine cabinet as well.
In 2007, some of the leading ichthyosis doctors from around the world met in Germany and started to talk about agreeing on common, standardized names for all the different types of ichthyosis. It wasn’t an easy task, for several reasons:
- there are at least 30 varieties
- some are just skin problems while others have additional issues
- there are at least 3 ways to classify them – genetics, symptoms, or what the biopsy looked like.
In 2009, the same group of doctors got back together, this time in France, and after much discussion and labor, they came up with a system. This system is published in a *cough* “concise” 34 page article in a fairly well-known dermatology journal, but it’s not something anyone other than dermatology doctors and researchers would ever read. Further complicating matters, the full text of the actual article isn’t freely available online. (Doctors and researchers can access it fairly easily through their various journal subscriptions, but those of us without access to those commercial databases are more-or-less out of luck.)
So, here’s the chart:
|Type||Old Name||New Name||New Name abbreviation||Genes|
|Common||Ichthyosis vulgaris||Ichthyosis vulgaris||IV||Fillagrin (FLG)|
|X-linked ichthyosis||X-linked ichthyosis||XLI||Steroid Sulfatase (STS)|
|Keratinopathic Ichthyosis (KPI)||Bullous Ichthyosiform Erythroderma (bCIE)||Epidermolytic Ichthyosis||EI||KRT 10|
|Epidermolytic Hyperkeratosis (EHK)||KRT 10|
|Palmoplantar Keratoderma (PPK)||KRT 1|
|BCIE of Brocq||KRT 10|
|Ichthyosis hystrix||Ichthyosis hystrix (Curth-Macklin)||KRT 1|
|Siemens type EHK||Superficial Epidermolytic Ichthyosis||SEI||KRT 2|
|Vohwinkel Syndrome||Loricrin Keratoderma||LK||LOR|
|Autosomal Recessive Congenital Ichthyosis (ARCI)||Harlequin Ichthyosis||Harlequin Ichthyosis||HI||ABCA12|
|Collodion Baby||Lamellar Ichthyosis||LI||ABCA12
|nonbullous congenital ichthyosiform erythroderma (nbCIE)||Congenital Ichthyotic Erhtyroderma||CIE||ALOXE3
|congenital ichthyosiform erythroderma (CIE)|
|congenital nonbullous ichthyosiform erythroderma (CNIE)|
Source: Oji, et. al., “Revised nomenclature and classification of inherited ichthyosis: Results of the First Ichthyosis Consensus Conference in Sorèze 2009, J Am Acad Dermatol. 2010 Oct;63(4):607-41.
First, they agreed that most of the world doesn’t get diagnosed from electron microscopy or from genetic testing. Most people get a diagnosis from what their skin looks like and whether anyone else in the family is affected. So, even though most of the genes are known now, they decided to leave the diagnosis at the eyeball level when trying to figure out what to call it.
Then, they split everything into two categories: (1) Just Skin (non-syndromic) and (2) Skin and Other Stuff (Syndromic). Then they split each category into what the problem is, and finally dominant and recessive varieties.
The experts who met in Sorèze in 2009 decided on two new umbrella terms. They decided that the term “keratinopathic ichthyosis”, or “KPI”, should describe the broad category of “generalized cornification disorders caused by keratin mutations”. And that the term “autosomal recessive congenital ichthyosis”, or “ARCI”, should be an umbrella term used to describe harlequin ichthyosis, the spectrum of lamellar ichthyosis and CIE.
So that’s still a bit confusing. One (overly general and imprecise) way to think about it is that KPI covers everything caused by a mutation in keratin making. ARCI covers everything to do with the skin growing too fast and not falling off in a timely fashion. Vulgaris and X-linked are by themselves, not falling off, but also not growing too fast.
The chart above only lists the non-syndromic types of ichthyosis. So Netherton’s syndrome isn’t on this chart because it’s a syndrome. The Sorèze paper describes all of syndromic types, too, but we’ll leave that discussion for another day.
So what does it mean for all of us? Well, here’s a bit of an explanation from our own “style sheet” when writing about ichthyosis. Hopefully, we’re being consistent!
For most types of epidermolytic ichthyosis, we will mention the former name the first time we talk about it in a post. So, for instance, our little buddy Ben has “epidermolytic ichthyosis, formerly known as epidermolytic hyperkeratosis (EHK)”. We have decided not to use the abbreviation “EI”, ever — because that’s just too much alphabet soup.
For forms of ARCI, we will continue using the short name specific to the type, but we we will introduce both names the first time we talk about it in a post. So, for example, our friend Hunter has “harlequin ichthyosis, the most severe form of autosomal recessive congenital ichthyosis (ARCI)”. And our friend Laura has “lamellar ichthyosis, a form of autosomal recessive congeinital ichthyosis (ARCI)”. We have decided that calling it “HI” or “LI” is also too jargon-y, and so instead we will noun the adjective and (as many people do already), will, in subsequent references, simply say “harlequin” or “lamellar”. However, since in our experience both patients and researchers have been used to talking about “CIE” as a shortcut for “congenital ichthyotic erythroderma”, we’ll continue to use that abbreviation, even though that gets us to the alphabet soup of talking about “CIE, a form of ARCI”.
In our own experience so far, we haven’t seen many references to “KPI”. At some point, we may start talking about “epidermolytic ichthyosis, a form of keratinopathic ichthyosis (KPI), and formerly known as epidermolytic hyperkeratosis (EHK)”. We’d love to hear from researchers (whether or not they attended the Sorèze conference), as to whether that extended recitation is worthwhile. (Admittedly, the extended recitation would be consistent with our treatment of ARCI, but the various forms of ARCI have less “renaming” in the post-Sorèze world.)
It may be obvious from our blog, but we think that making ichthyosis research accessible to non-scientists is really important. And one of the fundamental barriers to understanding ichthyosis literature is trying to figure out if the publication or the doctor or the researcher is even talking about the same type of ichthyosis that you have. Hopefully, everyone starting to use the “correct” terminology, as reflected by the consensus of the leading ichthyosis researchers who met in Sorèze in 2009,will make life easier.
Edited 10/30/2012: We wrote a followup post about the “new” names, addressing several questions and comments.