Orbital lymphoid tumors located predominantly within extraocular muscles.

Lymphoid masses can be centered predominantly within an extraocular muscle (EOM), as exemplified by computed tomography (CT) scanning and biopsy confirmation in the seven cases reported in this study. In these patients, an insidious and painless onset of exophthalmos was overshadowed by ptosis or a motility disturbance (particularly limited upgaze) in the absence of chemosis and lid erythema. The lesions were located in the superior rectus-levator complex (6 cases) and in the medial rectus muscle (1 case). One patient, with an exclusive infiltration of the levator, had a complete ptosis, whereas four others had a partial ptosis. Important clinical clues included palpable masses (4 cases) and preserved downward gaze (all cases), the latter suggesting the absence of fibrotic restriction, as is often seen in Graves' myopathy and the idiopathic myositis of pseudotumor. The biopsy specimens showed spill-over of the hypercellular and stroma-free lymphoid tissue into the orbital fat (all cases) and into the lacrimal gland (3 cases). Full extraocular motility on upgaze was restored after local orbital radiotherapy, although a residual ptosis persisted in five cases. Five patients had well-differentiated lesions and nonocular disease did not develop, whereas a widespread disease developed in one of two patients with a cytologically malignant lymphoma; the patient eventually died.