Cellulitis vs. Phlegmon

SNOMED Groups Translation User Group
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We had a discussion in the German Translation Group on Cellulitis and Phlegmone.

In German, “Phlegmone” is a commonly used medical term; “Cellulitis” exists, but is rarely used. The clinicians in our group see the terms as synonymous, others see a slight difference. There can be found sources for both views.

In SNOMED CT, there are several hundred “Celllulitis” disorders with the associated morphology “Cellulitis”. Although the morphologic abnormality “Phlegmon” exists as a child of cellulitis, there is only one disorder modelled with “Phlegmon” as associated morphology (735591005 |Acute phlegmonous appendicitis (disorder)|).

From the clinical perspective, we need “Phlegmon” disorder concepts. The GTG is divided if: We should just translate the “Cellulitis” concepts with “Phlegmone” - or create many new concepts with the morphologic abnormality “Phlegmon”.

Do other translators faced similar challenges? I have detected that the Netherlands edition has introduced an own concept 29891000146103 |Phlegmonous cellulitis (disorder)| (second option) and that the French translation in some cases uses “cellulite” and “phlegmon” synonymously, e.g. 75817003 |Cellulitis of breast (disorder)| (first option).

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Clinicians may not all apply the same criteria to distinguish cellulitis from phlegmon and medical sources don’t agree on the exact definitions, but it seems to be a question of severity and “boundaries” of the affected area.

Cellulitis would be an inflammation of the subcutaneous tissue without suppuration and more diffuse; phlegmon would be a septic inflammation of the superficial or deep connective tissue, that is more organized but still poorly defined, with an onset of suppuration, which could then progress to the formation of a well-defined abscess.

I don’t think they are perfect synonyms. And in French (at least in French Canadian), it’s quite the opposite: “phlegmon” is rarely used, except to translate “peritonsillar… abscess (!!) = phlegmon péri-amygdalien”, and “cellulite” is a commonly used medical term.

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Addition: I just got feedback from ICD-10 side. They have translated “Cellulitis” as “Phlegmone”. In the ICD-11 it was done the same way. Two more arguments that in German, “Phlegmone” should be treated as synonymous with “Cellulitis”, although it doesn´t reflect the morphologic abnormality modelling in SCT

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This seems to be a translation issue as cellulitis http://id.who.int/icd/entity/2144774073 and phlegmon http://id.who.int/icd/entity/644291175 are separate entities in the ICD-11 foundation, although there is no definition associated with the latter so the discriminating feature is not specified.

The primary differences between the two is as previously mentioned: severity of the infection, depth or boundary of the inflammation and the formation of pus in phegmon. However, it appears that in many recent scientific articles phlegmon and cellulitis are treated synonymously and sometimes both terms are used within the same manuscript, without making a differentiation.

https://ukrmedsci.com/index.php/stomat/article/download/328/311

So, as @mgagnon has stated, they are not perfect synonyms, but at this point it is not possible to get a differentiating definition. UpToDate treats them as synonyms in certain conditions and different in others. We would like to make this as unconfusing as possible and would like a consensus on whether to make them synonymous or not.

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From our medical expert: In Swedish, the term “flegmone” is seldom used and has an archaic feeling. The difference as pointed out is that “flegmone” is more spread cellulitis (“cellulit” in Swedish), often becoming an abscess. “Cellulit” is a serious infection but can be rather superficial and localized, som the difference here is that “flegmone” is the same but more serious cellulitis.

To sum it up:

In Swedish, only cellulitis is used, but what we call phlegmone is more serious.

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We indeed have our local concept of phlegmone. In Dutch, the concepts of cellulitis and phlegmone are distinct, where cellulitis is ‘only’ an infection of the dermis and the subcutaneous fat tissue and/or connective tissue, and phlegmone is defined as a more severe kind of infection which is suppurative/serous (Pinkhof Medical Dictionary). Additional sources state that it is a diffuse infection (Flegmone (flegmoneuze ontsteking)). It also has a synonym of necrotising cellulitis.

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@annatina to request definitions be added to Cellulitis and Phlegmon, and to enquire why phlegmon is not used to define 23587002 |Phlegmon of pancreas (disorder)| or concepts with “phlegmonous”.

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Please submit CRS requests to correct those errors.

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FEEDBACK FROM FRANCE:

Stefan Schulz steschu@gmail.com
Fr., 17. Apr., 11:25
an vianney, Nikiema, Fleur, Helmut, Sophie, DARMONI, Kokou, olivier.bodenreider

Hi Fleur, Vianney, Jean-Noel, Yvon, Olivier, and Stéfan,
@Helmut Dultinger , @Klopfenstein, Sophie Anne Ines (SNOMED CT translation group)

Let me approach you with a tricky SNOMED translation question, counting on your medical and terminological expertise. Helmut, Sophie and I are involved in SNOMED terminology translation, and we’ve had repeated discussions with colleagues from several countries within the SNOMED Translation User Group about the concepts Cellulitis, Phlegmon , and Erysipelas. The group disagrees whether Cellulitis and Phlegmon should be different disorder concepts.

In current SNOMED CT, there are disorder concepts for Cellulitis and Erysipelas but not for Phlegmon. Cellulitis has a very broad text definition. Erysipelas is under Cellulitis of Skin. In contrast, there are morphology concepts for Cellulitis and Phlegmon but not for Erysipelas.
“Phlegmon(e)” is frequent in German, Dutch and French, but less in English.
“Cellulitis” or “Zellulitis” is rarely used in German texts. In English, “Cellulitis” seems to be very common, much more than “Phlegmon”.

What is your opinion, according to your clinical and terminological experience and medical education?

Assuming
“Cellulitis” (E) = “cellulite” (F)
“Erysipelas” (E) = “érysipèle” (F)
“Phlegmon” (E) = “phlegmon” (F)

Would you agree that in French clinical and scientific discourse

“phlegmon” is narrower than “cellulite”, which would justify a separate SNOMED disorder concept? “phlegmon” would then be a child of “cellulite” and a sibling of “érysipèle”.

or that

“phlegmon” is increasingly being substituted by “cellulite”, following international trends and that two separate concepts are not necessary, and that “phlegmon” as a synonym of “cellulite” (“érysipèle” being a hyponym) better reflects current use of French clinical language?

Thanks in advance for your help, which is highly appreciated for consensus building in our group.

Stefan

--
Stefan Schulz
Univ.-Prof. Dr. med.
Institute for Medical lnformatics, Statistics and Documentation
Medical University of Graz, Auenbruggerplatz 2/5
A-8036 Graz, Austria
Tel: +43 316 385 16939 | +43 699 150 96 270
Email: stefan.schulz@medunigraz.at
Web: www.medunigraz.at/imi/ | purl.org/steschu

JOUHET Vianney über medunigraz.at
So., 19. Apr., 17:01
an Nikiema, Fleur, Helmut, Sophie, DARMONI, Kokou, olivier.bodenreider@gmail.com, Stefan

Hi Stefan,

In my opinion they are different concepts.
The cellulitis definition you provide from the snomed seems too broad to me because it should occur on the skin and subcutaneous tissus only (from my point of view). It can be complicated by a phlegmon thus involving deeper structure. But this assertion is not possible because then cellulitis and phlegmon would be siblings… So I won’t go that way!

However following the provided definition I would choose the subsuming proposition meaning that a phlegmon is a kind of cellulitis involving deeper structure (this does not mean that it has to involve skin or subcutaneous tissues overwise this wouldn’t be true).

So this one seems good to me : “phlegmon” is narrower than “cellulite”, which would justify a separate SNOMED disorder concept? “phlegmon” would then be a child of “cellulite” and a sibling of “érysipèle”.

Hope this can help

Vianney

Yvon Awuklu über medunigraz.at
Mo., 20. Apr., 05:35
an Vianney, jean, Fleur, DARMONI, olivier, Stefan, Helmut, Sophie

Hi Stefan,

In my view, phlegmon should be treated as a narrower concept than cellulite in French clinical practice, justifying a separate SNOMED disorder concept (i.e., phlegmon as a child of cellulite and a sibling of érysipèle).

The clinical distinction is meaningful: érysipèle refers to a superficial, well-demarcated infection, while phlegmon refers to a deeper, more diffuse infection of soft tissues with poorly defined borders.

Cellulite functions as the broader umbrella term covering both. These differences have clinical and therapeutic implications, which supports maintaining them as distinct concepts rather than collapsing them.

Regarding the second option — that phlegmon is increasingly being substituted by cellulite following international (primarily English-language) trends — I would be cautious about this.

While English-language literature heavily favors “cellulitis” and French practice is not immune to this influence, “phlegmon” remains a specific and commonly used term in French clinical and scientific discourse, although its use may vary depending on the clinical context. Replacing it with cellulite as a simple synonym would risk losing a clinically useful distinction that French-speaking practitioners still actively make. The ambiguity of “cellulite” in French (due to its widespread non-medical cosmetic usage) is an additional reason to preserve “phlegmon” as a precise, unambiguous clinical term.

Best regards,
Yvon

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The NRC Austria got an answer to its request for clarification by SNOMED International:

We have discussed this request internally as we are aware of the discussion about this topic on SNOMED Forums: https://forums.snomed.org/t/cellulitis-vs-phlegmon/986 The Netherlands extension has a concept: 29891000146103 |Phlegmonous cellulitis (disorder) which could have a synonym added of “Phlegmon”. As you mention, the Netherlands extension already includes relevant subtypes and uses the synonymous term “flegmone”. This aligns with the current SNOMED CT interpretation of phlegmon as a more severe suppurative subtype of cellulitis. Current discussions also concluded that cellulitis and phlegmon are not strictly synonymous; however, “phlegmonous cellulitis” is considered an appropriate representation for the clinical meaning commonly intended by the term “phlegmon/flegmone”. As the requested content overlaps with existing Netherlands extension content, we recommend following the SNOMED CT process for promotion of extension content into the International Edition. The next step would therefore be to contact the Netherlands NRC, as the manager of the owning extension is responsible for submitting any request for promotion of extension content to the International Edition. If the Netherlands NRC agrees, they can submit a promotion request for: 29891000146103 |Phlegmonous cellulitis (disorder)| and any associated subtype content. This approach would support international consistency and help avoid creation of duplicate overlapping concepts.

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Concept is requested for promotion in CRS

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@annatina kindly let us know when the concept has been promoted to the International Edition.

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@plammertyn The concept will be published in the 1 july SI version, is already visible in the daily build 29891000146103 |Phlegmonous cellulitis (disorder)|