[1430] MALT Lymphoma with Associated Amyloid Deposition – A Clinico-Pathological Study of 18 Cases

RJH Ryan, L Zukerberg, JM Sloan, B Collins, J Ferry. Massachusetts General Hospital, Boston, MA; Boston Medical Center, Boston, MA

Background: Extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma) occurs in a variety of extranodal tissues and typically follows an indolent clinical course. Prior descriptions of MALT lymphoma-associated amyloid are limited to case reports and small series.
Design: We searched the pathology files for cases of MALT lymphoma and amyloid. Cases were evaluated with in-situ hybridization, immunohistochemistry, and/or flow cytometry. Congo Red was performed in all cases. Frozen section immunofluorescence for kappa and lambda light chains, AA protein, and transthyretin was performed on four cases.
Results: We identified 18 patients with a total of 34 pertinent specimens. Six patients had a history of autoimmune disease. Primary sites included lung (4), soft tissue (4), skin (2), salivary gland (1), ocular adnexa (3), breast (1), base of tongue (1), small bowel (1), and thymus (1). All patients had MALT lymphoma, usually with prominent plasmacytic differentiation and Dutcher bodies. Amyloid ranged from microscopic deposits within lymphomatous infiltrates, to macroscopic nodules which often exceeded the volume of the adjacent lymphoma, and were initially misinterpreted as fibrous tissue on FNA in three cases. The lymphomas were CD20+(18), CD5-(14/15), CD10-(8), sIg+(1 K, 4 L), cIg+(16/17, 7 K, 10 L). Immunoflorescence demonstrated lambda (n=3) or kappa (n=1) light chain in amyloid deposits, which corresponded with the light chain expression of the underlying lymphoma, as well as absence of AA and transthyretin expression. Low concentration serum M-proteins were seen in 6 of 9 patients tested. Clinical follow-up (14 patients) ranged from 1 to 28 years (median 5 years) from initial lymphoma diagnosis. One patient died from progressive lymphoma and therapy-related myelodysplastic syndrome, while all others were alive at last follow-up. One patient developed slowly progressive renal insufficiency over five years, clinically attributed to her longstanding renal tubular acidosis, not amyloidosis. One patient experienced prolonged postoperative peripheral neuropathy. Several patients developed bulky, symptomatic amyloidomas. No patients developed cardiac failure.
Conclusions: MALT lymphoma-associated amyloid is an unusual form of localized AL amyloidosis that does not appear to be associated with systemic AL amyloidosis. Such cases can create significant clinical and diagnostic challenges, but usually demonstrate an indolent clinical course.
Category: Hematopathology

Monday, March 22, 2010 1:00 PM

Poster Session II # 146, Monday Afternoon

 

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