Spectrum of argyrophilic nucleolar organizer region (AgNOR) staining patterns in chronic and transformed B-cell leukemias.

Aspirates of bone marrow with chronic lymphocytic leukemia, hairy cell leukemia, and Richter's syndrome were stained by the argyrophilic nucleolar organizer region (AgNOR) method and analyzed. The AgNOR configurations of small cells of chronic lymphocytic leukemia, hairy cell leukemia, and lymphosarcoma cells were similar and most often consisted of a single large dot, a single small regular bleb, and two dots of various sizes, similar to patterns of normal lymphocytes. The large cells of chronic lymphocytic leukemia and prolymphocytic leukemia cells transformed from chronic lymphocytic leukemia contained larger AgNORs (group II), that is patterns consistent with proliferation. Richter's syndrome lymphoma cells contained even larger AgNORs. A single large regular bleb, small regular bleb and large irregular bleb were most common. Cells with only small structures were very rare.