AL amyloidosis with a localized B cell neoplasia.

Immunoglobulin light chain-derived (AL) amyloidosis may occur as a systemic disease usually with dismal prognosis and a localized variant with favorable outcome. We report 29 patients with AL amyloidosis and associated lymphoplasmacytic infiltrate spatially related to amyloid deposits. In 17 cases, the amyloid deposits were classified as ALλ and 12 as ALκ Histopathology in all cases showed relatively sparse plasma cells and B cells without tumor or sheet formation by the lymphoplasmacytic infiltrate. The B cells predominantly showed an immunophenotype of the marginal zone. In situ, hybridization revealed 17 cases with λ- and 10 with κ light chain restricted plasma cells, which was concordant with the AL subtype in each case. Clonal immunoglobulin heavy variable gene (IGHV) or κ light chain rearrangement was found in 23/29 interpretable cases. A single case harbored a MYD88L265P-mutation. Taken together, we detected 27 (93%) cases of AL amyloidosis with an associated light chain restricted and predominantly molecularly clonal plasma cell population. Clinical data were available in 18 patients. Five patients suffered from systemic lymphoma and two from systemic AL amyloidosis. The remaining cases were classified as localized with regard to both, the AL amyloidosis and the light chain restricted plasma cell population. To the best of our knowledge, we herein present the largest cohort of AL amyloidosis associated with a light chain restricted and predominantly molecularly clonal plasma cell population, which we designate as a distinct disease entity: "AL amyloidosis with a localized B cell neoplasia of undetermined significance".

Local vs. systemic pulmonary amyloidosis-impact on diagnostics and clinical management.

Immunoglobulin-derived light-chain (AL) amyloidosis of lungs and bronchi can appear as a systemic and a local form. While systemic AL amyloidosis may need haemato-oncological care, the localised form can be treated restrained. We re-evaluated 207 specimens of lungs and bronchi sent in for amyloid diagnostics. Amyloid was diagnosed by polarization microscopy using Congo red-stained tissue specimens and classified immunohistochemically. Histoanatomical amyloid distribution patterns were documented as well as additional histological findings. For 118 patients with AL amyloidosis, we retrieved clinical data. CT scan results were available from 59 patients. AL amyloidosis was the most common type (183 cases). ALλ was found in 141 and of ALκ in 27 cases. Fifteen cases were AL amyloid not otherwise specified. Twenty cases harboured transthyretin and three serum amyloid A derived amyloid. By correlation of histoanatomy, radiological and clinical data, amyloid was rarely in the initial differential diagnosis. Local AL amyloidosis often presented with a nodular pattern on CT scan and showed a significantly better disease-specific 10-year survival compared with systemic AL amyloidosis (96.0 vs. 51.9%). Localised and systemic pulmonary and bronchial AL amyloidosis are having a completely different prognosis. While CT scan might be indicative, histological and clinical assessment are mandatory to reach a proper diagnosis and guide patient care.