Astrocytoma Definition

An astrocytoma or astrocytic hamartoma is a benign tumor that develops from the astrocytes of the neuroglial tissue.

Epidemiology: Astrocytomas are rare.

Etiology: Astrocytomas belong to the phakomatoses and are presumably congenital disorders that develop from the layer of optic nerve fibers. They may manifest themselves as purely ocular disorders or in association with tuberous sclerosis (Bourneville's disease).

Symptoms: Patients usually have no ocular symptoms. Calcifying astrocytic hamartomas in the region of the basal ganglia or ventricles can cause epilepsy and mental deficiency. An astrocytoma in Bourneville's disease will be associated typically with an adenoma sebaceum in the facial skin.

Findings and diagnostic considerations: Astrocytomas are either incidental findings in ophthalmic examinations performed for other reasons, or they are diagnosed in patients presenting with reduced visual acuity. Ophthalmoscopy will reveal single or multiple "mulberry" tumors one to two pupil diameters in size. These will appear white and are often calcified. The tumors are inherently fluorescent when observed in blue light in fluorescein angiogra-phy with a blue filter.

Differential diagnosis: A retinoblastoma should be excluded in children. That is usually larger than an astrocytoma on ophthalmoscopy. A possible Toxocara canis granuloma should be confirmed or excluded by serologic studies.

Treatment: No ophthalmologic treatment is required. The patient should be referred to a neurologist to exclude cerebral involvement.

Clinical course and prognosis: These tumors rarely increase in size.

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