Anatomic Pathology: Vascular Pathology

• Cerebral arterial wall amyloidosis is a major cause for massive intracranial hemorrhage. Subcutaneous arteries are often affected in the setting of systemic amyloidosis, and deep subcutaneous abdominal fat aspirates (including Congo red incubations) can be helpful for establishing a diagnosis.

• Ischemic stroke may be the initial manifestation of amyloidosis. Risk factors for stroke are similar to the risk factors in the general population and include atrial fibrillation, hyperlipidemia, hypertension, and diabetes mellitus.

• CNS involvement is unusual in patients with the more common AL and AA amyloidosis. Amyloid deposits can lead to extensive cortical pathology and dementia in patients with sporadic or familial Alzheimer disease, whereas cerebral amyloid angiopathy can cause spontaneous cortical and subcortical intracranial bleeding, primarily in older adults.

• Vascular cerebral amyloid deposits are biochemically similar to the material comprising senile plaques in Alzheimer disease. The primary constituent of each is amyloid β peptide, a 39- to 43-amino acid fragment of the amyloid precursor protein. There is essentially no clinical overlap between vascular cerebral deposits and non-CNS systemic amyloidosis, such as primary (amyloid AL) and secondary (amyloid AA) amyloidosis.

• Sampling of subcutaneous tissue was introduced in the 1970s as a diagnostic technique for some systemic forms of amyloidosis and remains a valuable tool, either as aspiration of the abdominal fat pad or as deep biopsy of the subcutaneous fat performed by a dermatologist or surgeon. Initial studies involved fine needle aspiration, which has subsequently been used in some studies in combination with ultrastructural and immunohistologic analysis of tissue.