[Two cases of orbital myositis with 67Ga accumulation in the orbits]

We reported two patients of orbital myositis with abnormal accumulation of 6 Ga in the bilateral orbits. The first patient, a 34-year-old man, developed bilateral lid swelling and external ophthalmoplegia. T1-weighted MRI of the bilateral orbits showed enlargement of the bilateral extraocular muscles. 67Ga scintigraphy also showed abnormal accumulation in the orbits. The second patient, a 64-year-old woman, developed diplopia caused by restricted abduction of the bilateral eyes. 67Ga scintigraphy showed abnormal accumulation in the bilateral orbits, in spite of no finding in the MRI of the extraocular muscles. Both cases were treated with 1 g of methylprednisolone per day for 3 days and subsequently 1 mg/kg per day of oral prednisolone, which resulted in improvement of opthalmoplegia and disappearance of the abnormal accumulation of 67Ga in the orbits. There is no report about orbital myositis with abnormal accumulation of 67Ga in the orbit. Our cases suggest that 67Ga shows the activity of orbital myositis and can be useful for diagnosis, especially in case of no abnormality in MRI study.