Cyclical orbital eosinophilic myositis

Cyclical orbital eosinophilic myositis

Eosinophilic myositis is a rare inflammatory condition of skeletal muscle associated with peripheral eosinophilia.¹ Orbital eosinophilic angiocentric fibrosis² and idiopathic orbital myositis³ have been reported. We report the first case of cyclical orbital eosinophilic myositis (OEM).

Case report

A 38‐year‐old woman presented to the ocular motility service in January 2006 with a one‐week history of left‐sided ptosis and diplopia. In the past four years, she had reported alternating ptosis and retro‐ocular pain that recurred at six‐week intervals. She was systemically well. Cranial computed tomography, magnetic resonance imaging, tensilon testing, neurophysiology and anti‐acetylcholine receptor antibody had been normal.

Ocular examination revealed left partial ptosis, left hypotropia (20 prism dioptres (PD)) ipsilateral limitation of elevation, and ipsilateral temporal conjunctival hyperaemia (fig 1A, B). Visual acuity was normal bilaterally. Full blood count, inflammatory markers, serum angiotensin‐converting enzyme, autoimmune screen, thyroid antibody, Lyme and worm serology were normal. Chest X‐ray, thorax and abdominal computed tomography did not demonstrate regional lymphadenopathy or metastases. Magnetic resonance imaging scan showed increased signal in all rectus muscles (fig 1C). Presumed bilateral orbital myositis was managed with intravenous methylprednisolone 1 g a day for two days. The hypotropia and ptosis improved rapidly (2‐PD esophoria). She developed two recurrences over a 10‐week period, one affecting the right side (fig 2A). Incisional biopsy of the left lateral rectus muscle demonstrated extensive disruption of the skeletal muscle by lymphoid aggregates with abundant eosinophils (fig 2B). This was reviewed by the national centre for tropical medicine and the regional reference laboratory. There were no histological features to suggest parasitic infection, and a diagnosis of OEM was made. Maintenance steroid therapy was started; however, the condition has remained unresponsive (fig 2C). Topical cyclosporin A has been tried without effect, and the patient, who remains disabled by these episodes, has declined any further intervention.

Figure 1 (A) A 38‐year‐old‐woman with a left partial ptosis (left upper lid is kept open during testing) and limitation of elevation. There is a 20‐PD left hypotropia. (B) Severe engorgement of the conjunctival and episcleral vessels overlying the left lateral rectus muscle. (C) Magnetic resonance imaging scan performed on presentation in 2006. Coronal short τ inversion recovery sequence of the orbits. Increased signal is present within all recti muscles bilaterally, particularly the left lateral rectus and superior rectus muscles bilaterally. Informed consent was obtained for publication of this figure.

Figure 2 (A) Second episode two months after presentation. An almost complete right‐sided ptosis, a 35‐PD right hypotropia, and limitation of right elevation. (B) Biopsy specimen of left lateral rectus muscle. Striated skeletal muscle is extensively disrupted by lymphoid aggregate. The infiltrate consists of numerous macrophages together with abundant eosinophils, in a sparse background population of small lymphocytes. There is no evidence of lymphoid neoplasia or other malignancy. (C) Six months after presentation on maintenance steroid treatment. Right hypertropia (patient often preferentially fixed with paretic eye), left upper lid retraction, limitation of left elevation and left episcleritis. Informed consent was obtained for publication of this figure.

Comment

Cyclical OEM is previously unreported. It is a benign inflammation with a cyclical frequency and chronic course. Important clinical features include alternating ptosis, large‐angle vertical ocular deviations up to 50 PD, and episcleral inflammation. A review by the regional clinical immunology unit confirmed a non‐infectious, immune‐mediated OEM. The pathogenesis of OEM may represent an abnormal activation of ocular allergic inflammatory mechanisms.⁴ Allergy‐inducing T‐helper type 2 cytokines such as IL‐5 and eotaxin promote the activation and degranulation of eosinophils⁵ within ocular skeletal muscle. Focal necrosis of extra‐ocular skeletal muscle fibres leads to a self‐limiting ocular myopathy. Eosinophils may persist in tissue, and recurrent reactivation may account for the cyclical frequency in our patient. Muscle is recognised to be resistant to apoptosis, and in inflammatory myopathies muscle fibres do not die.⁶ In our patient, a complete recovery of extra‐ocular muscle function occurred between attacks. Our biopsy did not reveal any signs of myofibrosis. High‐dose intravenous steroids appeared to be effective early on; however, OEM becomes steroid‐resistant over time. Newer immunomodulatory therapy may play a role in reducing the duration of episodes and delay recurrence.⁷ Cyclical OEM is an unusual condition that is diagnosed by exclusion and early ocular muscle biopsy is advisable.

Acknowledgements

The authors would like to thank Professor P L Chiodini, Department of Parasitology, London School of Tropical Medicine and Hygiene, for his opinion in the case and review of the pathology sample.