Dual amyloidosis: A clinicopathologic and proteomic analysis of 111 patients

Patients with two different amyloid types are rare. It is critical to identify all types of amyloid in a patient as amyloid therapies vary dramatically depending on the specific precursor protein.

To analyze the clinicopathologic and proteomic features in patients with two types of amyloid.

We queried our reference laboratory database of 51,309 amyloid specimens from all anatomic sites typed by mass spectrometry-based proteomics (LC-MS/MS) for patients diagnosed with two different amyloid types. Demographic data (patient age, sex, and anatomic site), mass spectrometry proteomic features, and clinical history, when available, were reviewed.

We identified 111 patients with two amyloid types: 83 male (75 %), 28 female (25 %). The median age at initial diagnosis was 78 years (range 45-96 years). 56 patients (50 %) had cardiac involvement. The two amyloid types were present either in the same anatomic compartment within a single specimen (48 patients, 43 %), in different anatomic compartments within a single specimen (43 patients, 39 %), or in two different anatomic locations (20 patients, 18 %). The most common combination was AL plus ATTR (69 patients, 62 %), which occurred in 68 % of patients with cardiac involvement.

It is crucial to identify all amyloid types in all cases, including careful morphologic review to evaluate for distinct areas with different distribution, and consider the possibility of a second amyloid type when the clinical findings are not explained by the initial amyloid type. In some patients, this may require biopsy from a second anatomic site.