Bilateral Paraneoplastic Orbital Myositis Associated With Malignant Melanoma and Multiple Myeloma

Paraneoplastic extraocular muscle enlargement has been reported in a small number of patients with cancers including breast or lymphoma, usually presenting with bilateral multiple muscle involvement. Such myositis may be autoimmune. Furthermore, orbital inflammation is a recognized complication of immune-modulation therapy used to treat melanoma, such as ipilimumab. Extraorbital myositis has been described in myeloma, and polymyositis in melanoma. We present a case of bilateral, asymmetrical extraocular muscle enlargement with spontaneous resolution in a patient with simultaneous new diagnoses of metastatic malignant melanoma and multiple myeloma. A similar episode 7 months before diagnosis also resolved spontaneously. The authors believe this to be the first reported case of paraneoplastic orbital myositis associated with multiple myeloma or untreated malignant melanoma.