B-cell monocytoid lymphoma a low-grade lymphoma in which cells resemble those of hairy cell leukemia.
From: McGraw Hill Conside Dictionary of Modern Medicine:
Hematology A low-grade B-cell lymphoma affecting lymph nodes and extranodal sites is the malignant counterpart–ie, a clonal expansion of monocytoid cells—in reactive lymphoid hyperplasias arising in a background of toxoplasmosis and other benign lesions.