Cerebral amyloidoma

Cerebral amyloidomas are the rarest manifestation of cerebral amyloid deposition, typically appearing as solidly enhancing masses. 

Epidemiology

Reported numbers are low due to the rarity of this condition, making generalizations about epidemiological features difficult. Generally, cases have been reported in patients of middle age (30 to 50 years of age) with perhaps a female predilection ^1,2. Of the four manifestations of cerebral amyloid deposition, amyloidomas appear to be in the youngest cohort.

Clinical presentation

Clinical presentation is non-specific and depends on the location of the mass. Generally, symptoms include focal neurological deficits, seizure, headaches and decline in cognitive function ^1,2. This is in no way helpful in distinguishing cerebral amyloidomas form other intracerebral masses. 

Pathology

Cerebral amyloidomas are composed of large nodular masses of cerebral amyloid-β (Aβ) ¹. These are centered in the white matter with deposits in the wall and surrounding blood vessels, with adjacent inflammatory cells ¹. 

Radiographic features

Cerebral amyloidomas are characterized by nodular solid masses with vivid contrast enhancement, typically centered within the white matter, often abutting the lateral ventricles ¹. They are and surrounded by a mantle of vasogenic edema ¹. They have most commonly been reported as solitary lesions centered in the white matter of the cerebral hemispheres, although cortical and even posterior fossa lesions have been described ¹. 

These masses typically grow only slowly if at all, and generally appear to exert less mass effect than one would expect from a similar sized tumor ¹. 

CT

Amyloidomas generally are somewhat hyperattenuating, although hypoattenuating examples have been reported ^1,2.  Following administration of contrast, these masses usually enhance ². 

MRI

Signal characteristics of the mass are variable ^1,2. 

• T1: variable signal intensity, ranging from hypointense to hyperintense
• T2: variable signal intensity, ranging from hypointense to hyperintense
• T1 C+
  • vivid contrast enhancement
  • peripheral radial enhancement is sometimes seen, thought to correlated with vessel wall cerebral amyloid-β deposition ¹
• T2*/SWI: microhemorrhages may be seen

Treatment and prognosis

Cerebral amyloidomas are benign and surgical resection, which is the treatment of choice for symptomatic individuals is generally curative, although recurrences have been documented ¹. Even in asymptomatic individuals, resection or biopsy are usually undertaken as it is difficult to confidently differentiate these lesions from primary or secondary tumors ². To date, no specific medical therapy has been identified as useful ¹. 

Differential diagnosis

The differential diagnosis of cerebral amyloidomas is largely that of tumors of the central nervous system, including:

• CNS lymphoma
• high grade gliomas
• cerebral metastases