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Bilateral Ocular Myositis as a Late Complication of Dermatomyositis To the Editor: Dr. Kokotis and colleagues have given an excellent description of an interesting clinical case1. It was recognized as bilateral ocular myositis based on the clinical features and orbital magnetic resonance imaging (MRI) showing enlargement of the recti extraocular muscles (their Figure 1). Nevertheless, if we make a closer inspection of Figure 1, it will not be difficult to find that only coronal sections of the orbital MRI were presented, but the important radiological section, an axial section, of the involved recti muscles was missing. Axial imaging plays a key role in diagnosis, absence of which may blur the distinction between this case and thyroid eye disease2,3. The clinical manifestation of ocular myositis may sometimes be vague and difficult to distinguish from thyroid eye disease or Graves' ophthalmopathy2. Both these conditions may produce extraocular muscle enlargement on orbital imaging; but characteristically, extraocular muscle enlargement of thyroid eye disease tends to be tendon-sparing, whereas in ocular myositis, the inflammatory change is more diffuse and involves the whole muscle bellies and tendons2,3. This marked imaging disparity is best appreciated from the axial sections of orbital scans2. Apart from computerized tomography or MRI orbital imaging, ophthalmic echography (B-mode ultrasonogram) may act as a supplement to the clinical difficulty in distinction between the two. Surprisingly, given that thyroid eye disease is the most common cause of bilateral proptosis in adults, the authors have apparently given no consideration of it as a differential during the clinical investigation. In the interest of readers, the authors are encouraged to provide more information for this patient, particularly investigatory results such as axial MRI of the orbit and thyroid function tests. DAVID T.L. LIU, MRCS, Department of Ophthalmology and Visual Sciences, Prince of Wales Hospital, Shatin, Hong Kong. E-mail: david_tlliu@yahoo.com; ALICE Y.K. CHAN, MRCP, FHKAM(Rheumatology), Social Hygiene Service, Department of Health, Hong Kong, People's Republic of China. REFERENCES 1. Kokotis P, Theodossiadis P, Bouros C, Sfikakis PP. Bilateral ocular myositis as a late complication of dermatomyositis. J Rheumatol 2005;32:379-81. 2. Scott IU, Siatkowski MR. Thyroid eye disease. Semin Ophthalmol 1999;14:52-61. 3. Slavin ML, Glaser JS. Idiopathic orbital myositis: report of six cases. Arch Ophthalmol 1982;100:1261-5. |
