Internal medicine and clinical immunology

What is internal medicine and clinical immunology?

Internal medicine is defined not by an organ but by a method. The cardiologist deals with the heart, the nephrologist with the kidney; the internist deals with the whole patient when the signs fit into no box. He sees people referred by another doctor for a fever that persists, an unexplained biological inflammation, an unusual combination of symptoms that several specialists have examined separately without connecting them. His work consists first in reconstructing a complete history, and only then in deciding which investigations make sense. The Société nationale française de médecine interne, the learned society of the specialty, describes a comprehensive and thorough medicine intended for patients who have several diseases, places the internist between the general practitioner and the organ specialist, and takes up from Fred Siguier the phrase according to which he is "the natural counterpart to excessive specialisation". It names four referral situations: involvement of several organs, complex diagnoses, rare or orphan diseases and autoimmune or systemic diseases, and older people with several diseases. Training bears the mark of this: internal medicine residency lasts five years where most specialties last four, because of the versatility required. [S1]

Clinical immunology is the other half of the title, and it is the less well known to the public. The function of the immune system is to recognise what is foreign and destroy it. In certain diseases it mistakes its target and attacks the person's own tissues: these are the autoimmune diseases. In others it is triggered on its own, with neither microbe nor autoantibody, and produces flares of fever and inflammation: these are the autoinflammatory diseases. In others again it works poorly by default and lets infections through. The clinical immunologist is the one who can read this disturbance in a given patient, choose the tests that measure it and conduct the treatments that correct it. In France, the two terms form a single specialty title: the orders published in the Journal officiel that authorise the practice of medicine name the specialty "médecine interne et immunologie clinique", internal medicine and clinical immunology. [S2] There is, on the other hand, no reference text in French that defines clinical immunology as the Société nationale française de médecine interne defines internal medicine; this gap is real and the section "What is not known" says so rather than filling it with an invented formula.

His work on this subject

This page has no corpus of its own and that is normal: there is no article "of internal medicine" in the sense in which there are articles on VEXAS syndrome or on antiphospholipid syndrome. What the method produces is seen in the results obtained on the diseases that the thirteen other pages set out. Seven pieces of work, grouped according to the five things this method can do, are taken up here with their exact figures.

Recognising an association that no one had measured. A French retrospective multicentre study published in Rheumatology (Oxford) in 2016, of which Arsène Mekinian is 1st of 40 named authors, brought together 123 patients with both a myelodysplastic syndrome and a systemic inflammatory or autoimmune disease, and compared them with 665 patients with a myelodysplastic syndrome or a chronic myelomonocytic leukaemia without any manifestation of this kind. Mean age was 70 years, the male to female ratio 2. The manifestations were a systemic vasculitis in 39 cases (32%), a connective tissue disease in 31 cases (25%), an inflammatory arthritis in 28 cases (23%), a neutrophilic dermatosis in 12 cases (10%) and remained unclassified in 13 cases (11%). One figure from this study says on its own what the daily work of the discipline is: the disease met the usual classification criteria in 75 cases (66%), but these criteria were not met in 21 cases (19%). One patient in five therefore fitted no established definition, and yet had to be diagnosed and treated. One hundred and eighteen patients (96%) were treated, 91% of them with corticosteroids, with 83% response at first line, but a second line was necessary in 48% of cases for corticosteroid dependence or relapse. Overall survival did not differ between the two groups (P = 0.5). ² The subject is developed on the page "Myeloid haematological disorders and inflammatory manifestations".

Looking for the single cause behind two apparently distinct diseases, and for the rare cause behind a commonplace presentation. In 2019, a case report published in Haematologica, which he co-signs in 10th position of 16 named authors, describes in one patient an Erdheim-Chester disease and a chronic myelomonocytic leukaemia carrying the same clonal mutation. It is an isolated case, and an isolated case demonstrates nothing on its own; it does, on the other hand, illustrate exactly the reasoning of the discipline, which consists in asking whether two diseases occurring in the same person are not in fact one. ⁴ The same year, a piece of work published in Seminars in Arthritis and Rheumatism, which he co-signs in 21st position of 23 named authors, takes the problem from the other end: starting from a national registry of IgG4-related disease and a review of the literature, it assesses the place of this disease among the causes of pachymeningitis, that is inflammation of the covering of the brain. In a regional referral centre, IgG4-related disease accounted for 10% of inflammatory pachymeningitis; conversely, in the national registry of IgG4-related disease, pachymeningitis represented 4.1% of cases. Eight new cases are reported and 46 histologically proven cases are reviewed. Involvement remained isolated in the majority of cases: only 27% of spinal forms and 40% of cranial forms were accompanied by another site of the disease. An immunosuppressant or rituximab was necessary in 18% of spinal forms and 54% of cranial forms. ³

Describing a disease that has no chapter in the textbooks. Chronic histiocytic intervillositis is an inflammation of the placenta that is seen only on microscopic examination after a pregnancy loss, and that recurs. A prospective multicentre study published in Autoimmunity in 2015, of which he is 1st of 18 named authors, included between 2011 and 2013 all patients with an ongoing pregnancy after a history of chronic histiocytic intervillositis. Twenty-four women, aged 34 plus or minus 5 years, were followed; an autoimmune disease was present in seven of them (29%). Twenty-one prospective pregnancies were treated, that is 88% against 13% of the previous pregnancies. The number of live births was higher than in the same women's previous pregnancies, 16 out of 24 against 24 out of 76 (p = 0.003), that is a shift from 32% to 67% live births in the treated pregnancies. No difference appeared between the treatment regimens compared with one another. The risk of preterm delivery remained 30% despite treatment, and the risk of recurrence of an adverse outcome likewise 30%. ¹ The subject is developed on the page "Inflammatory placental disease".

Measuring a treatment where the randomised trial does not exist. Many systemic diseases are too rare for a placebo-controlled trial to be feasible. The discipline answers this with multicentre series built on common criteria. The study published in Rheumatology (Oxford) in 2022, of which he is 1st of 54 named authors, brought together 209 patients with Takayasu arteritis, of median age 29 years, of whom 186 women (89%), treated either with a tumour necrosis factor alpha antagonist (132 patients, 63%, 172 treatment lines) or with tocilizumab (77 patients, 37%, 121 lines). A complete response at six months was observed in 101 patients out of 152 (66%) on a tumour necrosis factor alpha antagonist and in 75 out of 107 (70%) on tocilizumab. Over a median follow-up of 36 months, 103 relapses were recorded. Adverse events occurred in 58 cases (20%). The study is retrospective and the patients were not randomly allocated between the two strategies: it describes what was observed, it does not demonstrate the superiority of one treatment over the other, and its authors indeed conclude that efficacy and drug retention were equivalent. ⁵ The subject is developed on the page "Large-vessel vasculitis".

Writing the common rule once the cases have been gathered. The end point of the reasoning, in a rare disease, is a text that tells French teams what to do. The national diagnostic and care protocol for Cogan's syndrome, published in La Revue de médecine interne in 2025, was drawn up under the aegis of the CeRéMAIA reference centre and the FAI²R network; the record published by the network states that it was written under the coordination of Prof. Arsène Mekinian, and he is its 26th and last named author, and also corresponding author. ⁶[S3] The document describes a vasculitis of unknown cause that affects the cornea and the inner ear, notes that general manifestations are present in 30 to 70% of patients and a biological inflammatory syndrome in 75% of cases, and states clearly the limit of the field: no prospective randomised study has been conducted to date in this disease, which deprives management of a consensus founded on trials. The same exercise has been carried out at international level for VEXAS syndrome: a guidance statement of the American College of Rheumatology published in Arthritis & Rheumatology in 2026, of which he is 1st of 58 named authors, brought together an international panel to establish, through a formalised process of meetings and voting, practical considerations on the clinical manifestations, screening of the UBA1 gene, the diagnosis of an associated myelodysplastic syndrome, prognosis and management. This document presents itself as a guidance statement, not as recommendations; its authors write that it constitutes the first formal international consensus on this disease and that it arose from the finding that no clinical document existed to guide clinicians. ⁷ The subject is developed on the page "VEXAS syndrome".

Passing on the method. A discipline that rests on a method is judged also by what it teaches. Arsène Mekinian has directed the university diploma in reproductive immunology of Sorbonne Université since 2024, of which he is the academic lead: 70 teaching hours, attached to the faculty of Health, academic year 2026-2027 open in the catalogue. [S4] The national register of doctoral theses, `theses.fr`, makes it possible to measure doctoral supervision without going through any declaration: his own science thesis appears there, defended on 6 January 2017 on the regulatory B cell population in chronic lymphocytic leukaemia, prepared at Université Sorbonne Paris Nord in the laboratory Adaptateurs de signalisation en hématologie; to which are added four doctoral theses that he co-supervised and that were defended at Sorbonne Université between 2019 and 2025, on follicular helper T cells in systemic sclerosis (2019 and 2025, laboratory of the Centre de recherche Saint-Antoine), on a treatment decision support tool for lupus, systemic sclerosis, Takayasu disease and antiphospholipid syndrome (2023), and on cardiovascular risk in systemic sclerosis and giant cell arteritis from a national registry and the Système national des données de santé (2025). He has in addition chaired two thesis juries in 2022 and 2024 and been rapporteur for two theses defended in 2025 in Bordeaux and Strasbourg. [S5] These subjects cover the three groups of the site, which shows that the discipline is one there and not a collection of juxtaposed specialties.

The thirteen other areas of work. This page is the point of entry and the point of return of the thirteen that follow. Reproductive immunology: "Reproductive immunology", "Recurrent early pregnancy loss", "Recurrent implantation failure", "Inflammatory placental disease", "Antiphospholipid syndrome", "Pregnancy and autoimmune diseases". Autoimmune and autoinflammatory diseases: "VEXAS syndrome", "Autoinflammatory diseases and inflammatory amyloidosis", "Systemic autoimmune diseases", "Large-vessel vasculitis", "Systemic sclerosis". Haematological disorders and treatments: "Myeloid haematological disorders and inflammatory manifestations", "Immunomodulatory treatments".

Where care is organised

The department of internal medicine of Saint-Antoine Hospital (AP-HP), 184 rue du Faubourg Saint-Antoine, 75012 Paris, itself describes its activity as the care of patients with autoimmune diseases, non-malignant haematological diseases, rare or orphan diseases, difficult diagnoses, or several diseases at once. Diagnostic work-up, administration of treatments and follow-up take place there in outpatient consultation, in day hospital or in conventional inpatient care. [S6] Arsène Mekinian practises there as professor and hospital consultant; he is not the head of department. The page of Sorbonne Université Formation Continue concerning him presents him as "professeur des universités - praticien hospitalier en médecine interne et immunologie clinique à Sorbonne Université, dans le service de médecine interne de l'hôpital Saint-Antoine (AP-HP), depuis 2019" (university professor and hospital consultant in internal medicine and clinical immunology at Sorbonne Université, in the department of internal medicine of Saint-Antoine Hospital, AP-HP, since 2019). [S4] It is the only institutional statement that brings together the two halves of the title of this page. On the AP-HP practitioner record, the specialty displayed is "Médecine interne" alone: the hospital directory carries the specialty of practice, the university carries the academic title.

The department houses several rare disease structures, and it matters to distinguish what belongs to him from what belongs to other practitioners of the same department. A rare disease reference centre is a hospital structure accredited by the ministry responsible for health; it comprises a coordinating site and constituent sites, to which are added local competence centres. A rare disease health network is not a centre: it is a coordinating structure that links the centres of a single field to one another. Arsène Mekinian coordinates the Saint-Antoine Hospital constituent site of the reference centre for autoinflammatory diseases and inflammatory amyloidosis, CeRéMAIA, which has seven sites in France. The centre's teams page names him among the seven site leads, for adults, with as themes VEXAS syndrome, clonal haematopoiesis and inflammation, and inflammatory manifestations associated with haematological malignancies. [S7] The directory of the rare autoimmune and autoinflammatory disease health network, FAI²R, states that the centre located at Saint-Antoine Hospital is coordinated by him and publishes the list of the site's referring physicians in internal medicine, rheumatology, neurology, cardiology, haematology and intensive care, supplemented by referring physicians in nephrology, dermatology and respiratory medicine at Tenon Hospital, in obstetrics and gynaecology at Trousseau Hospital and in ophthalmology at the Centre national d'ophtalmologie des Quinze-Vingts. [S8] The professional record of Orphanet, the European reference resource for rare diseases, attributes to him the roles of clinical expert, coordinator of an expert centre and principal investigator of a clinical trial, and mentions only one expert centre, that same constituent site. [S9] The other rare disease structures housed by the department, including a constituent reference centre for bradykinin-mediated angioedema accredited in 2016 and a competence centre for adult autoimmune cytopenias, have other practitioners of the department as their leads and do not come under him; they are therefore not carried here.

Difficult decisions are not taken alone. The FAI²R network organises national multidisciplinary team meetings, open to any doctor following a patient with a rare autoimmune or autoinflammatory disease, throughout the country. These are referral meetings: the network asks that the case first have been presented to local or regional meetings where these exist. They are held on a platform approved for the hosting of health data, bring together a quorum of experts from at least three different specialties under the conduct of a session coordinator, and each case gives rise to a report validated by that coordinator, sent to the doctor who presented the case and added to the patient's file. The network states that it exceeded one hundred cases discussed in the first year and has discussed more than two hundred each year since. [S10] Arsène Mekinian appears for internal medicine in the quorum of twenty-four experts of the national MINHEMON meeting, devoted to systemic manifestations of haematological malignancies, which is held by video conference on Tuesdays from about 17:00 to 18:00 every two weeks and where each case is presented by the patient's referring doctor. [S11] These meetings are a mechanism for advice between doctors; they do not constitute a route of access for a patient who would like a consultation, and access to the department goes through a request made by the doctor following the patient.

The research side is attached to the Centre de recherche Saint-Antoine, a joint Inserm and Sorbonne Université unit, whose current contract runs from January 2025 to December 2029. Two spellings of the unit number coexist depending on the source, "Inserm UMR_S 938" in publication addresses and on the centre's site, "unité Inserm U938" on the page of Sorbonne Université Formation Continue. That same page presents him as co-founder and coordinator of FRENVEX, the French study group on VEXAS syndrome, and as founder and president of the MINHEMON network. [S4] These two networks have no publicly consultable administrative existence and are cited here as the university institution declares them.

What is not known

The first limitation is that of the methods used, and it applies to most of the work cited on this site. The five studies taken up above are all observational: four are retrospective and the fifth, prospective, has no control group. They describe what was done and what happened, they do not compare two randomly allocated strategies. The 2016 study on systemic manifestations of haematological malignancies brings together 123 patients recruited in many centres with no common treatment protocol. ² The study on Takayasu arteritis compares two families of treatment in 209 patients who were not allocated at random, which makes it impossible to attribute the observed difference to one or the other. ⁵ The prospective study on chronic histiocytic intervillositis concerns only 24 women and compares their treated pregnancies with their own previous untreated pregnancies: this historical comparison is not equivalent to a control group, and the authors do not in fact separate the treatment regimens from one another. ¹ The 2019 work on IgG4-related pachymeningitis adds eight new cases to 46 cases drawn from the literature, which exposes it to publication bias. ³ The case of Erdheim-Chester disease associated with a chronic myelomonocytic leukaemia is a single case. ⁴ None of these results has been replicated in a controlled trial.

The second limitation lies in the synthesis texts themselves. A national diagnostic and care protocol and an international guidance statement are expert agreements, obtained by discussion and by voting, and not the conclusions of trials. The Cogan's syndrome protocol says so itself: no prospective randomised study has been conducted in this disease. ⁶ The guidance statement of the American College of Rheumatology on VEXAS syndrome was constructed precisely because no sufficient data existed, and presents itself as an aid to decision, not as a demonstrated rule. ⁷ Such documents age quickly in diseases where the biology is advancing.

The third limitation is that of the discipline itself, and it is unusual: clinical immunology has, in French, no reference text that defines it. The Société nationale française de médecine interne publishes a detailed definition of internal medicine; no equivalent French institutional source has been found for clinical immunology. What is established amounts to two points: French law names the specialty "médecine interne et immunologie clinique" in the practice authorisation orders published in the Journal officiel, and several French university hospital departments bring the two terms together in their title. What this page says of clinical immunology in its first section is therefore a description in plain language, written to be understood, and not the reproduction of a reference text, for want of one existing.

The fourth limitation is that the method itself has never been measured. There is no study comparing the outcome of patients cared for according to an internal medicine method with that of patients cared for otherwise. The value of comprehensive reasoning about a patient who has several diseases is intuitive and it is accepted by the organisation of care; it is not demonstrated in the sense in which the efficacy of a drug is demonstrated. This must be said, in particular on a page that presents this method.

Finally, the definition of internal medicine taken up in the first section comes from the Société nationale française de médecine interne and is not a text by Arsène Mekinian. [S1] The description of the national multidisciplinary team meetings comes from the pages of the FAI²R network and is likewise not his. [S10][S11]

References

Published work he has taken part in, on this subject.

• Chronic histiocytic intervillositis: outcome, associated diseases and treatment in a multicenter prospective study — Autoimmunity, 2015 1st of 18 named authors; consortium "SNFMI and the European Forum of APS" outside the count; MEDLINE type Multicenter Studycited 60 times
• Systemic inflammatory and autoimmune manifestations associated with myelodysplastic syndromes and chronic myelomonocytic leukaemia: a French multicentre retrospective study — Rheumatology (Oxford), 2016 1st of 40 named authors; MEDLINE type Multicenter Studycited 176 times
• Clinical presentation, treatment and outcome of IgG4-related pachymeningitis: From a national case registry and literature review — Seminars in Arthritis and Rheumatism, 2019 21st of 23 named authors; MEDLINE type Reviewcited 30 times
• Erdheim-Chester disease associated with chronic myelomonocytic leukemia harboring the same clonal mutation — Haematologica, 2019 10th of 16 named authors; consortium "MINHEMON and EMSED" outside the count; MEDLINE type Case Reports; the record carries no abstract free full textcited 22 times
• Efficacy and safety of TNF-α antagonists and tocilizumab in Takayasu arteritis: multicentre retrospective study of 209 patients — Rheumatology (Oxford), 2022 1st of 54 named authors; consortium "French Takayasu network" outside the count; MEDLINE type Multicenter Study
• French protocol for diagnosis and management of Cogan's syndrome — La Revue de médecine interne, 2025 26th of 26 named authors, last author and corresponding author; `CN` line "contributors" outside the count; MEDLINE type Practice Guideline
• American College of Rheumatology Guidance Statement for Diagnosis and Management of VEXAS Developed by the International VEXAS Working Group Expert Panel — Arthritis & Rheumatology, 2026 1st of 58 named authors; `FIR`/`IR` lines and consortium "International VEXAS working group" outside the count; MEDLINE type Practice Guideline; published online on 11 August 2025 free full textcited 15 times

General information only. This page does not replace individual medical advice. Updated: 10 September 2026.