Follicular lymphoma with PAS-positive amorphous material: report of two cases.

Extracellular, PAS-positive material has been described in various lymphoproliferative disorders, but is rare in malignant lymphomas. We report two such cases of grade 2 follicular lymphoma that were investigated by routine H&E histology, immunohistochemistry, flow cytometry, and molecular pathology. Ancillary studies confirmed the monoclonality in each case and the antigenic similarity to the neoplastic cells, with the exception of bcL-2. One possible pathogenic mechanism for this extracellular material may be the exocytosis of overproduced cell membranes.