Gastrointestinal B-cell lymphomas: From understanding B-cell physiology to classification and molecular pathology

Figure 4 Polymerase chain reaction. A: Polyclonal B-cell pathology results in a broad smear of the polymerase chain reaction (PCR) product on a gel, while a monoclonal pathology (lymphoma) will give rise to a sharp band on a gel, hereby reflecting PCR products that have the same size. +C: Positive control; -C: Negative control; 6592: Tumor case; 6590: Reactive case; B: Gaussian curve in a polyclonal B-cell population examined by multiplex PCR; C: Peak in a neoplastic B-cell clone examined by multiplex PCR.