Skin involvement in generalized amyloidosis. A study of clinically involved and uninvolved skin in 50 patients with primary and secondary amyloidosis.

A punch or excisional biopsy of the skin was done in 50 patients with generalized amyloidosis: In 46, clinically normal skin, usually the forearm, was biopsied and in four, only cutaneous lesions. Amyloid was seen in the skin of 21 of 38 patients with primary and multiple myeloma-associated amyloidosis. Sixteen of 34 biopsies from clinically uninvolved skin were positive. Five of 12 patients with secondary amyloidosis had amyloid deposits in clinically normal skin. Overall, amyloidosis was definitively diagnosed on skin biopsy examination in 26 patients. A punch biopsy of clinically involved or uninvolved skin is an innocuous, simple procedure with a high diagnostic yield and can be done in an office setting.