Neuro-ophthalmology: Case eight
This 27 year-old woman presented with a six month history of painless vertical diplopia (figure 1). An orbital scan was requested and appeared as shown in figure 2.
a. What do the pictures show?She has a left partial ptosis and downward displacement of the globe. The CT scan shows a space occupying lesion in the left lacrimal fossa without bony destruction.
b. What is the most likely diagnosis?The history and the CT scan appearance is suggestive of a left benign mixed tumour (pleomorphic adenoma) of the lacrimal gland.
This is a slow growing tumour and structurally consists of both epithelial and mesenchymal tissues. Pain is absent and the symptoms is caused by the mass effect of the tumour which can produce motility problem, diplopia and non-axial proptosis. On the CT scan the tumour is smooth and well delineated due to the firm fibrous tissue. Bone destruction is not seen but erosion from pressure effect may occur.
c. What is the differential diagnosis of the appearance shown in figure 2?Apart from pleomorphic adenoma, lesion in the lacrimal fossa include:
- malignant epithelial tumour of which adenoid cystic carcinoma is the most common. Pain is common and there is rapid onset of signs and symptoms (proptosis, diplopia and poor motility). Bony destruction is common and the tumour spread to the middle cranial fossa early. The prognosis is poor.
- metastatic tumour
- lymphoid tumours
- inflammatory which may be idiopathic or related to other systemic condition such as sarcoidosis
d. How would you manage this patient?en bloc excision is the treatment of choice if the history and radiological appearance appears benign. Biopsy of the tumour can violate the pseudocapsule leading to recurrence and possible malignant transformation.
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