Bone marrow core biopsy specimens in AL (primary) amyloidosis. A morphologic and immunohistochemical study of 100 cases.

We retrospectively reviewed 100 bone marrow core biopsy specimens from patients with AL (primary) amyloidosis. The morphologic and immunohistochemical features were assessed by standard histochemical stains (H&E, periodic acid-Schiff, Congo red) and immunohistochemical stains for light chain immunoglobulins. Bone marrow core biopsy revealed a plasma cell dyscrasia in 83% (lambda, 65; kappa, 18) of cases. Amyloid deposits were observed in 60% of the bone marrow core biopsy specimens and, when present, were detected most often in blood vessel walls only (39/60). However, if present, interstitial amyloid deposition was significantly more associated with patients with a monoclonal kappa light chain gammopathy (P = .04). Through the careful analysis of standard histochemical and immunohistochemical stains, bone marrow core biopsy provides essential diagnostic information in cases of AL amyloidosis.