Teaching Case

7-year-old girl with swollen, thickened, indurated skin on the right wrist, inability to clench fist and flex elbow for 3 months. No fever or other systemic features.

Vitals were stable. Subtle hyperpigmentation, non-pitting oedema and warm right upper and lower limb.

Clinically, differentials were morphea and lymphoedema.

Laboratory investigations revealed raised absolute eosinophilic count (>1500/cumm) with normal TLC. Mildly elevated ESR (43mm).

MRI of both forearms and screening MRI scans of both arms and lower limbs were performed.
MRI of both forearms revealed right-sided involvement more than left side with marked superficial as well as deep fascial and intermuscular septal thickening and oedema involving both the anterior and posterior compartment. There was also mild adjacent muscle oedema in the dorsal compartment (Fig. 1a, b). No evidence of fatty infiltration in the muscles (Fig. 1c).
MRI of both lower limbs also showed significant right-sided and minimal left-sided fascial and deep intramuscular septal thickening and oedema in thighs as well as calves (Fig. 2a, b).
Right arm had mild fascial thickening and oedema with relative sparing of the left arm (Fig. 3a, b).

Background:
Eosinophilic fasciitis, a rare disease entity, is also referred to as Shulman’s syndrome (1974) [1, 2]. The disease causes inflammation of the fascia, predominantly involving the distal peripheral extremities. The aetiopathogenesis is not clear [1].

Clinical Perspective:
Eosinophilic fasciitis clinically presents with skin manifestations, which may mimic scleroderma [2]. Classically, it is acute in onset and presents with cutaneous oedema and induration. It predominantly affects the distal parts of the extremities and is usually symmetric [1]. Laboratory findings include hypergammaglobulinaemia, elevated erythrocyte sedimentation rate and peripheral eosinophilia (raised absolute eosinophilic count) [2]. Imaging helps in confirmation of clinical diagnosis, guidance for optimal location for biopsy and evaluation of response to therapy. The triad of clinical features, peripheral eosinophilia and hypergammaglobulinaemia are diagnostic. Biopsy is not pathognomonic but suggestive and can be avoided.

Imaging perspective:
MRI can help identify superficial, deep fascia and intermuscular septa separate from the muscle belly. The oedema centred around the former would suggest fasciitis and the latter myositis. The oedema from one can extend to involve the other, however, the epicentre is important to identify.

In eosinophilic fasciitis, predominant fascial oedema and thickening is best appreciated on fluid sensitive sequences, oedema can extend into adjacent hypodermic fat and muscle [1, 2]. Fascial enhancement can also be seen on post-gadolinium acquired images.

Myositis [1] (related to polymyositis, dermatomyositis and inclusion body myositis) is a close differential with predominant edema in the muscles and relative sparing of the fascia. Other differentials include stasis edema, cutaneous scleroderma in which the edema and involvement is usually limited to the hypodermic soft tissue [1]. Necrotising fasciitis is commonly associated with abscess and air foci may be seen [1].

Biopsy can help in further confirmation [2], however, is not pathognomonic but suggestive of diagnosis. Clinical and laboratory investigations with radiological correlation can confirm diagnosis and avoid a biopsy.

Outcome:
The treatment is medical with administration of steroids and methotrexate. The prognosis is better compared to morphea and scleroderma.

Take-home message, teaching points:
If imaging reveals predominant fascial involvement (rather than muscle) affecting the extremities, the suspicion for eosinophilic fasciitis should be raised. Further correlation with clinical presentation and laboratory investigations should be recommended to confirm the diagnosis.

The triad of clinical features, peripheral eosinophilia and hypergammaglobulinaemia are diagnostic. Radiological findings support the diagnosis and may also prompt the clinician to think about it retrospectively if not thought of prospectively as it is a rare entity, and thus avoid biopsy.