A unique case of foreign-body associated orbital myositis.

A 50-year-old woman presented with a 2-week history of diplopia and right-sided orbital pain with eye movement. Examination revealed an edematous, ptotic right upper eyelid with conjunctival hyperemia, proptosis, and significant limitation to upward and downward ductions on the right. MRI was significant for a homogeneously enhancing lesion within the superior rectus muscle. A laboratory evaluation seeking an infectious, inflammatory, or autoimmune process was nonrevealing. A diagnosis of orbital myositis was made, and the patient experienced significant improvement with oral corticosteroids. The patient's symptoms, however, recurred after attempts at a slow taper of the corticosteroids. An orbital biopsy of the lesion revealed fibroadipose tissue containing irregularly shaped yellow-white deposits birefringent under polarized light, suggestive of silica crystals. The patient denied any history of trauma or prior surgery. An intraorbital triamcinolone injection to the superior orbit allowed resolution of symptoms and a successful taper off systemic corticosteroids.