Dermatopathologic findings in 20 cases of systemic amyloidosis

The clinical findings of systemic amyloidosis are often variable and nonspecific. The early recognition of this disorder relies upon clinical suspicion, and definite diagnosis requires the confirmation of amyloid deposits in tissue. We reviewed 31 skin biopsy specimens from 20 patients, including 17 with amyloid light chain (AL) protein amyloidosis and 3 with serum amyloid A (AA) protein amyloidosis. Histologically, amyloid can be present in the papillary dermis, reticular dermis, subcutis, around the appendages, and in or around blood vessels. In our series, all 20 patients had at least one positive skin biopsy. Amyloid was found in 30 of 31 specimens (97%), a higher rate than in most series. Skin biopsy is a simple, safe procedure with high yield and may be used to obtain a firm diagnosis of systemic amyloidosis.