Eosinophilic fasciitis (EF) is an uncommon connective tissue disorder marked by symmetrical, painful swelling accompanied by progressive induration and thickening of the skin and soft tissues. The diagnosis of EF typically relies on the presence of distinctive skin or subcutaneous irregularities, alongside thickened fascia exhibiting inflammatory infiltration predominantly consisting of lymphocytes and eosinophils. Peripheral eosinophilia is often observed but is not essential for the diagnosis of EF.[1] Initially, it was characterized as an unusual form of scleroderma associated with eosinophilia and fasciitis. Nonetheless, the lack of sclerodactyly, Raynaud’s phenomena, visceral involvement, and positive response to systemic glucocorticoid administration identified the disorder as a distinct condition.[2]

The induration progresses and can result in joint contractures in around half of patients. In Caucasian populations, the prevalence among women is twice that of men. In approximately 25% of circumstances, involvement is limited to the lower legs; however, it is more common for all four limbs to be adversely impacted. The face has consistently been spared, despite reports of occurrences involving the trunk.[3] The largest series to date has reported only 63 patients, indicating that the disease is indeed rare.[4] This case report details the clinical manifestations of a 48-year-old female patient diagnosed with EF after a deep biopsy involving fascia and muscle.

A 48-year-old female, with previous diagnoses of dyslipidaemia and hypothyroidism, presented with complaints of bilateral progressive lower limb pain, oedema, pruritus across the bilateral dorsum of the feet for four months, and discolouration of the medial toes of both feet for one month (Figure 1).

Figure 1: Clinical presentation

The discomfort in both lower limbs primarily affected the calf muscles, presenting with a gradual onset and cramping characteristics. It was first observed after five minutes of walking, subsiding with rest and re-emerging upon additional ambulation. She also observed a colour alteration in the medial three toes of both lower limbs. She had consulted a dermatologist for itching and received medication but the symptoms recurred upon cessation of the medicines.

She was moderately built and nourished at the time of the examination, with a BMI of 23 Kg/m2. She was alert and orientated to time, place, and person, exhibiting no pallor, jaundice, cyanosis, clubbing, or lymphadenopathy. No local increase in temperature was recorded. Bilateral lower limbs had non-pitting pedal oedema accompanied by slight erythema, extending to the level of both knees. The condition was poorly delineated, featuring hyperpigmented plaques and mild skin thickening on the medial surfaces of both feet. Discolouration of the skin covering the medial three toes and the adjacent dorsum of both feet was observed.

The systemic examination indicated a blood pressure of 110/60 mmHg, a pulse rate of 86 beats/minute, and a respiratory rate of 18 breaths/minute. The patient was afebrile with a SpO2 of 99%. Moreover, feeble peripheral pulsations were observed in the lower extremities (dorsalis pedis and posterior tibial). The ankle-brachial pressure index was 0.8. The joints exhibited no indications of arthritis, and the neurological assessment, motor system evaluation, and cerebellar symptoms of the patient were unremarkable.

Laboratory testing indicated a total peripheral blood leukocyte count of 11,300 mm³, accompanied by an absolute eosinophil count of 5,260 cells per microlitre. The peripheral blood smear had eosinophilic predominance, with no aberrant cells or microfilariae identified. Liver and renal function tests were within normal limits, and hepatitis markers were negative. The erythrocyte sedimentation rate was 25 mm/hour. The Magnetic resonance imaging (MRI) indicated irregular mid-STIR hyperintensities without aberrant post-contrast enhancement in the intramuscular plane of the leg muscles, predominantly observed in the posterior and medial regions (Figure 2),

Figure 2: MRI of the bilateral legs

suggesting probable inflammatory alterations consistent with myositis. Bilateral mild subcutaneous oedema was observed, predominantly in the lower leg region, and may be associated with cellulitis. No pathological signs were observed in the lung X-rays or electrocardiographic examinations. The ultrasonographic examination of the upper abdomen revealed a grade-1 fatty liver. A vein Doppler ultrasound test found no evidence of deep vein thrombosis. The arterial Doppler examination indicated widespread atherosclerotic alterations, mostly characterised by calcified plaques and vessel wall calcification affecting the arteries of both lower limbs. Both dorsalis pedis arteries exhibited a monophasic spectral pattern.

The punch biopsy of the foot demonstrated extensive eosinophilic infiltrates primarily affecting the deeper dermis and subcutaneous tissue (Figure 3).

Figure 3: Punch biopsy from the foot

The patient was subsequently discharged with antihistamines, routine medications, and further supportive interventions. She was subsequently evaluated on an outpatient basis for a deep biopsy, encompassing fascia and muscle, to rule out EF. The histopathological assessment of the biopsy specimen demonstrated an epidermis exhibiting acanthosis, with the upper and mid-dermis displaying a slight perivascular infiltration of eosinophils and lymphocytes. The deep dermis and subcutis exhibited strong infiltration of eosinophils, along with a limited presence of histiocytes and lymphocytes. Additionally, mild fibrosis was observed. These findings have been considered to be consistent with EF associated with peripheral vascular disease. The patient was initiated on oral glucocorticoids at a dosage of 40 mg daily. Upon follow-up, the patient exhibited remission with substantial improvement in the clinical manifestations.

The diagnosis of EF is frequently challenging, leading to potential delays in therapy, as exemplified by the patient in question. The definitive diagnostic criterion for EF is a full-thickness skin biopsy that includes fascia and muscle tissue. Lymphocytes, eosinophils, plasma cells, and macrophages typically infiltrate the fascia in biopsies for EF; however, if the patient has previously received systemic corticosteroids or immunosuppressive medications, the eosinophils may be transitory.[5] MRI is likely the most comprehensive and informative of the imaging examinations,[6] illustrating the hypertrophy of the fascia, with alterations correlated to disease progression and therapeutic response.[7]

The pathophysiology remains unclear; however, it is hypothesised that the elevation of eosinophils induces an upsurge in transforming growth factor-β (TGF-β) that subsequently stimulates fibroblasts to synthesise excess collagen. Additionally, those with EF exhibit a higher concentration of metalloproteinase inhibitor protein type 1, which impedes collagen degradation, resulting in tissue fibrosis due to an augmented immune response.[1] One study found a rise in IL-5 and TGF-β concentrations in a 3-year-old child with EF, which was reverted with clinical recovery after steroid treatment.[8] Oral corticosteroid medication is the primary treatment for EF and proves successful in more than 90% of instances, yielding a favourable prognosis. Postponing treatment may result in joint contracture and persistent skin rigidity, with both aesthetic and functional consequences. Early in the course of the disease, it is crucial to establish a definitive diagnosis and distinguish it from other sclerotic conditions.[5]

Fibrosing disorders of the skin are among the differential diagnoses; it is especially crucial to distinguish them from systemic sclerosis due to the latter's organic involvement.[1] From a therapeutic perspective, three semiologic indicators may be beneficial in this context: the first is the lack of Raynaud’s phenomenon in EF, whereas it is an almost ubiquitous finding in systemic sclerosis. The second characteristic is the lack of distal involvement in EF, whereas this is the first impacted region in systemic sclerosis. The third indicator is the "V-sign," which is notably indicative of profound cutaneous involvement. Additional differential diagnoses encompass T-cell lymphoma, hypereosinophilic syndromes, cutaneous fibrosing diseases, and vasculitis associated with polyangiitis and eosinophilia.[9]

The diagnosis of EF may be disregarded during standard clinical assessments. The conclusive diagnosis of EF is established through deep biopsy and MRI, resulting in diagnostic delays. Timely identification and intervention of EF may positively influence patient morbidity, mitigate enduring dermal and muscular damage, enhance quality of life, and potentially contribute to disease remission.

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