Dulcor

Rubor, tumor, calor, dolor … and the sweet sign inflammation never had

Around AD 30, in the reign of Tiberius, the Roman encyclopaedist Aulus Cornelius Celsus, whose status as a practising physician remains uncertain, set down four words that medicine has spent two thousand years failing to improve upon.

Notae vero inflammationis sunt quattuor: rubor et tumor cum calore et dolore
The marks of inflammation are four: redness and swelling, with heat and pain

Rubor. Tumor. Calor. Dolor. You can see the first two and feel the last two. The splinter, the boil, the hot red joint, the body lighting a bonfire to burn out a threat. Twenty centuries of immunology later, the quartet still survives every viva, usually mangled at 3 a.m. by an exhausted intern into “rubor, timor, calor… door.”

The fifth sign, and a small act of myth-making

With functio laesa (loss of function), there were five. The joint that will not bend, the lung that will not fill. In almost any textbook the fifth sign is handed to Galen, the second-century colossus of Pergamon. A good story, but almost certainly, a fabrication.

Galen did not, so far as the surviving corpus shows, set functio laesa beside Celsus’s four as a fifth cardinal sign. As Leland J. Rather laid out in his 1971 synopsis of the legendary fifth cardinal sign, the tag functio laesa cannot be found in the Galenic corpus at all. The familiar five-part formula appears to be a much later synthesis, subsequently projected back onto Galen.

The later addition has been attributed variously to Thomas Sydenham and Rudolf Virchow. In his 1858 lectures on Die Cellularpathologie, Virchow placed disturbed function at the centre of cellular disease and is often credited with formalising functio laesa as the fifth sign. His association between chronic inflammation and tumour formation followed in Die krankhaften Geschwülste, published from 1863.

We are not the first to covet a place at Celsus’s table. Gerontologists have proposed penuria defining scarcity and the slow bankruptcy of cellular reserve, as a fifth sign of ageing.

All five describe the same fire

Together, the five signs form the fingerprint of acute inflammation, the hot, red, fast bonfire that flares and, mostly, resolves. The fire of the splinter and the strep throat. The fire Celsus could watch with his own eyes from across the atrium.

But another inflammatory fire does much of its damage unseen. It is cold. It smoulders for thirty years and then announces itself, fully grown, as a myocardial infarction, a stroke, dementia, or tumour. It travels under modern names such as metaflammation and inflammaging. On the surface it shares almost nothing with Celsus. No rubor. No calor. No dolor to drive the patient through your door. By the time there is functio laesa, the building has already burned to the joists.

You cannot see this fire. You cannot feel it. Which is precisely why it has been so easy, for so long, to look straight past it.

The accelerant is sweet

So what helps feed the cold fire? One answer is sugar. Not merely as calories, but as chemistry.

When a sugar meets a protein and no enzyme is there to chaperone the introduction, the two fuse, rearrange, and refuse to let go. This is the Maillard reaction. The browning of toast and seared steak running quietly at 37°C inside your own tissues, with no cook and no flame. Its later products include advanced glycation end-products (AGEs), a heterogeneous collection of molecular caramels, some of which cross-link collagen, stiffen tissues or engage inflammatory signalling.

Some AGEs bind RAGE and activate NF-κB signalling, helping to sustain a low-grade inflammatory response. Dietary AGEs and sustained hyperglycaemia approach the problem from different directions, but both may add to the glycative burden (Paparo et al., 2024).

It is, in the most literal biochemical sense, sweet inflammation. It has pathways, receptors, biomarkers and acronyms. What it lacks is a cardinal sign.

Dulcor

We would like to give it one.

Dulcor (genitive dulcoris) is a Late Latin third-declension noun derived from dulcis, “sweet”. The fourteenth-century mystic Richard Rolle even paired it with calor in the triad calor, canor, dulcor: heat, song and sweetness. We are simply changing the pathology.

By a small grammatical grace, it carries the same -or ending as the four elders:

Rubor. Tumor. Calor. Dolor. Dulcor.

It scans. It belongs. Dulcor names the dimension the original four miss, the silent, sugar-driven, glycative inflammation that wears no colour, throws no heat, and inflicts no pain until the damage is long done. The classical signs describe the fire you detect with your eyes and your hands. Dulcor describes the fire you can detect only with chemistry.

Sweetness also has medical pedigree. Pliny described saccharon as an imported “honey collected in reeds… brittle to the teeth… and used solely for medicinal purposes.” Two thousand years on, the medicine is in everything, and we are still arguing about the dose.

Can you see dulcor?

Many tissue AGEs fluoresce. A desktop skin autofluorescence reader can turn a faint signal into a numerical estimate of long-term tissue AGE accumulation. The measurement correlates with biopsy-derived AGE markers and has been associated with cardiovascular events and mortality, although it remains an indirect biomarker rather than a literal view of glycation.

It is, more or less, a way to see dulcor, the glycative burden hidden from the naked eye. Celsus had his fingertips. We have a UV lamp.

A modest proposal

Celsus was a close observer of medicine whose four words outlived every credentialled physician of his century. We offer dulcor in the same spirit. Not to unseat rubor, tumor, calor, dolor or their disputed cousin functio laesa, but to finish the thought by naming the sweet, cold, smouldering process quietly ageing us from within.

Dolor is what brings the patient to the door.
Dulcor is what has been burning, unseen, for thirty years before they arrive.

Aulus Cornelius Celsus, handed a skin reader and a flat white, might understand the proposal in an afternoon. Two thousand years later, we are still trying to make the invisible visible.

References

eponymythology

the myths behind the names

more eponyms
Prof Pete Smith Allergy Immunology LITFL author 3 2

Prof Pete Smith, MBBS, BMedSci, PhD (molecular immunology), FRACP. Australian based allergist and immunologist founder of Queensland Allergy Services. Active member of the Australasian Society of Clinical Immunology & Allergy, and a regular expert commentator in the media

BA MA (Oxon) MBChB (Edin) FACEM FFSEM. Emergency physician, Sir Charles Gairdner Hospital. Passion for rugby; medical history; medical education; and asynchronous learning #FOAMed evangelist. Co-founder and CTO of Life in the Fast lane | On Call: Principles and Protocol 4e| Eponyms | Books |

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