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).
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.
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
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.
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.
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.
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.
@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”.