Extraocular muscle enlargement as an isolated finding

Abstract

The authors report IS cases of orbital pathology, in which an enlargement of one or more extraocular muscles was the prevalent or isolated finding on CT-scan; in six cases, an MRI had been carried on as well. No other orbital masses were evident on images. Six patients were affected by Graves' disease, three by a myositis, two by an orbital metastasis, one by a lymphoid tumor, one by a cellulitis, one by a recurrent rhabdomyosarcoma and one by orbital varices.

In some cases, such as in Graves' disease and diffuse pseudotumor, the muscular changes were pathognomonic, especially if combined with clinical features; but other situations needed a challenging differential diagnosis. In particular, the differentiation of atypical isolated myositis from neoplastic conditions may prove to be impossible radiologically, requiring biopsy since some kinds of tumor (such as metastases) show extremely varied radiological patterns. The study of vascular abnormalities is greatly helped by clinical observation, but should be completed by arterio-graphy and venography. In this series, no particular advantage was found in the use of MRI as compared to CT, except for the possibility of obtaining direct multiplanar sections.

Key Words:

• extraocular muscles
• orbit
• CT-scan
• MRI
• Graves' disease
• myositis
• metastasis
• lymphoid tumor
• cellulites
• rhabdomyosarcoma
• varices