Thyroid Orbitopathy Obscuring the Diagnosis of a Rare Neuromuscular Hamartoma of the Superior Rectus Muscle in an Adult

Abstract

A neuromuscular hamartoma is a rare benign tumour that is most frequently associated with peripheral nerves.

The authors present a case of a 61 year-old man with bilateral exophthalmos and lid retraction who developed further proptosis and chemosis in the left eye over a five month period. An initial diagnosis of thyroid orbitopathy was made and he had a limited response to two courses of oral steroid administered in another centre. He was subsequently referred to our institution for further management when his condition worsened following withdrawal of treatment. Orbital CT scan showed a thickening of the recti muscles and particularly the left superior rectus and overlying soft tissue. Given this unusual pattern of muscle involvement in thyroid orbitopathy, a muscle biopsy was performed. This showed the presence of a neuromuscular hamartoma without malignant features. The orbital fat biopsy showed no pathological findings.

A neuromuscular hamartoma not associated with a peripheral nerve is a rare entity, especially when coupled with an extraocular muscle. We wish to highlight the importance of a muscle biopsy when faced with a clinical picture and radiological pattern of extraocular muscle enlargement not typical of what we know to occur traditionally in thyroid eye disease.

KEYWORDS::

• Neuromuscular hamartoma
• Extraocular muscle
• Orbit

Declaration of interest: The authors wish to declare that no funding has been received to carry out this study and that there is no conflict of interests.