How it begins
In most patients the disease begins over the course of weeks to a few months, insidiously. Only a few cases have a sudden, “overnight” onset. Most often the first signals that patients notice in hindsight are:
- Asymmetric, modest swelling of one or both lower limbs — initially blamed on tiredness or hot weather
- Morning stiffness of the limbs, easing over a few hours
- Muscle pain of unclear location (myalgia)
- Joint pain without visible inflammation (arthralgia)
- An unusual sensation of “heaviness” or “discomfort” in the limbs
- A feeling of “skin stretched tight”, particularly around the forearms and shins
Importantly: in a large proportion of patients, disease onset is temporally linked to intense physical effort (returning to training after a break, hard manual work, a major home renovation, long hikes) or to a mechanical injury of a limb. There is no “blame” in that effort — the effort does not cause the disease. In a susceptible person it probably becomes one of the possible triggers.
Among patients there is a running joke about “the kitchen renovation” — so many M35.4 stories start with a week of hard physical work that it has become an in-joke in patient groups. From a medical standpoint: the trigger is a catalyst, not the cause.
Inflammatory phase (first weeks–months)
In the first weeks from onset, inflammatory features dominate. The skin of the affected areas is:
- Swollen — the swelling is symmetric or very close to symmetric on both sides (rarely strictly unilateral)
- Warmer to touch than the rest of the body
- Reddened — often with a subtle erythema, sometimes with a fine rash
- Painful — particularly on pressure and on passive limb extension
- Firmer in depth than the swelling alone would suggest — a finger pressing the tissue leaves no typical pit, or the pit refills very quickly
The range of motion in the joints of the affected limb begins to be slowly restricted. At first imperceptibly, but over a few weeks the patient starts to struggle with simple motions: putting palms together overhead, a deep squat, putting on shoes. This is not a rheumatoid-type joint stiffness — it is a mechanical restriction because the deeper tissues do not want to stretch.
Peau d’orange and groove sign — the signature features
As the disease progresses, two highly characteristic signs appear. Together they are nearly pathognomonic (i.e. sufficient to strongly suspect M35.4).
Peau d’orange (“orange peel skin”)
The skin of the affected area takes on the appearance of an orange peel: tiny depressions visible at the openings of hair follicles and sweat pores, forming a “dimpled” pattern. It is best seen with a gentle skin pinch between the fingers — the pattern then becomes obvious.
It arises because the skin “adheres” to the thickened fascia below. The natural mobility of the skin layer over the deeper tissues disappears.
Groove sign
This is a linear, elongated depression running along the course of a superficial vein — most often visible on the forearm or shin. It appears when the vein “sinks” into the affected, hardened fascia surrounding it on every side.
Practical test: raise the limb above heart level and wait for several tens of seconds for the veins to empty of blood. In healthy tissue the skin surface remains smooth. In M35.4 — where the vein runs, a clearly visible groove appears.
The absence of peau d’orange or groove sign does not exclude a diagnosis of M35.4 — especially in the very early or very advanced stage of the disease. They are signs classic of the intermediate phase.
Fibrotic phase
If the disease is untreated, over a few months the inflammation transitions into chronic fibrosis. The inflammatory features (warmth, redness, pain) gradually subside — but the tissues do not return to normal. Instead they become:
- Hard “like a board” — without warmth, without pain, but rigid
- Colourless or slightly pale, sometimes with hyperpigmentation
- Permanently restricting joint range of motion
- Capable of leading to joint contractures — a fixed restriction of motion despite muscle strength
The most disabling are contractures in joints that cannot be straightened (e.g. a fixed elbow flexion, restricted forearm supination, ankle contractures). The later treatment is started, the higher the risk that these changes become permanent.
General symptoms
In some patients, beyond the local changes, there are systemic features:
- General fatigue — out of proportion to activity (50–70% of patients)
- Weight loss in the active phase, sometimes chronic
- Low-grade fevers (rarely fever >38°C)
- Myalgia — muscle pain, most often in the thighs and arms
- Arthralgia — joint pain without clinical joint inflammation
- Reduced exercise tolerance — quicker fatigue with ordinary activities
In individual patients, associated entities are also described: carpal tunnel syndrome (median nerve compressed by thickened tissues), coexisting morphea (localised scleroderma), or — very rarely — haematological disorders (peripheral cytopenia, aplastic anaemia).
Distribution of lesions on the body
Eosinophilic fasciitis has a characteristic — though not always identical — distribution of lesions:
- Most often: bilateral forearms, shins (around the calves)
- Frequently: upper arms, thighs
- Less often: trunk (especially chest, abdomen)
- Exceptionally: neck, face
- Classically spares: fingers and toes, hands and feet
This last point — sparing of the fingers — is one of the key features distinguishing EF from systemic sclerosis, in which finger hardening (acrosclerosis) is sometimes even the first symptom.
Frequency of involvement reported in Lakhanpal's series and subsequent work. Fingers and toes are spared in classic EF — one of the main features distinguishing it from scleroderma.
Bilateral forearms and shins are the classic battleground — involved in about 90% of patients and almost always the first regions a rheumatologist examines. Upper arms and thighs follow at 60–70%, and trunk involvement (chest, abdomen) appears in about a quarter of cases. Face and neck are rare exceptions. Fingers, hands and feet are essentially never involved in classic EF — this distribution is the single most useful pattern for separating M35.4 from systemic sclerosis at the bedside.
Lakhanpal 1988 · Bischoff & Derk 2008 · Mango 2020
What is usually absent in M35.4
A list of absent symptoms is sometimes diagnostically more valuable than a list of present ones. Absence of the following — alongside a peau d’orange / groove sign skin picture — strongly points to M35.4 rather than another scleroderma-like disease:
- Raynaud’s phenomenon (blueness/pallor of fingers in cold) — absent in EF
- Acrosclerosis (hardening and thinning of the fingers) — absent
- Fingertip ulcers — absent
- Telangiectasias (dilated vessels) on the face and hands — absent
- Swallowing disorders, oesophageal reflux — absent
- Lung involvement (interstitial lung disease) — not typical
- Kidney, oesophageal, cardiac involvement — absent
- Nailfold capillary changes (capillaroscopy) — normal
A rheumatologist who sees a patient with swelling and hardening of the limbs first does one thing: looks at the fingers. If the fingers are free — they think M35.4. If the fingers are involved — they think scleroderma. That is a three-second test that decides which way the diagnostic workup will go.
The list a rheumatologist runs through when torn between an EF and SSc diagnosis. “●” means present, “○” — absent or typically not seen.
The table reads as the bedside checklist a rheumatologist runs through when torn between an EF and an SSc diagnosis: every ‘no’ on the left lines up with a ‘yes’ on the right. The single most decisive item is finger involvement — acrosclerosis and Raynaud's phenomenon are the rule in SSc and essentially absent in EF. Eosinophilia and steroid responsiveness flip the picture the other way. None of these features alone is sufficient, but four or five matched rows make the diagnosis almost binary in clinical practice.
Lebeaux & Sène 2012 · Mazori 2017 · Onajin 2022
When to see a doctor
There is no “universal moment” at which to see a doctor, but there are signals that should not be ignored for longer than 2–4 weeks:
- Bilateral, persistent limb swelling without an obvious cause (after excluding deep-vein thrombosis, heart failure, renal failure)
- Gradually progressive restriction of joint range of motion in the elbows, shoulders, knees — especially symmetric
- Skin change: emerging peau d’orange or groove sign
- Reduced exercise tolerance combined with muscle pain
- Blood test results showing peripheral eosinophilia (>0.5 × 10⁹/L) without an allergological/parasitic explanation
The first doctor to consult is the family physician. If they suspect a systemic connective-tissue disease — they refer to a rheumatologist. In most Polish university centres, the initial EF workup is carried out by rheumatologists; a dermatologist joins when the differential with morphea is in play.
The time from symptom onset to diagnosis in M35.4 is, in the median, 6–11 months (varies by source — in some series even longer). That is a lot. The earlier treatment starts, the lower the risk of permanent contractures. If you recognise yourself in the symptoms described here — do not delay.
Sources
Full bibliography in the final version. Main sources:
- Mango RL, et al. Int J Rheum Dis 2020; 23: 233-239 — analysis of 89 Mayo Clinic patients.
- Lakhanpal S, et al. Semin Arthritis Rheum 1988; 17: 221-231 — classic series of 52 cases.
- Bischoff L, Derk CT. Int J Dermatol 2008; 47: 29-35 — demographics and clinical picture.
- Lebeaux D, Sène D. Best Pract Res Clin Rheumatol 2012; 26: 449-458 — comprehensive clinical review.
- Onajin O, et al. Expert Rev Clin Immunol 2022; 18: 707-718 — clinical guide “at the interface” of dermatology and rheumatology.