Cutaneous B cell lymphoma: diagnostic use of monoclonal antibodies.

A patient presented with a solitary plaque initially interpreted on light microscopy as benign lymphoplasia. Monoclonal antibody studies were used to define the B cell origin of the infiltrate and to characterize its probable malignant potential. Monoclonal antibody typing is a useful technique to evaluate lymphocytic infiltrates that may be difficult to categorize on the basis of routine light microscopy.