CCND1 and MALT lymphoma: Typical MALT lymphoma cells often present as small to medium-sized lymphocytes with moderate cell mass and nuclear irregularities, similar to the follicular center cells, and are thus called “central cell-like cells.” In immunohistochemistry, MALT lymphoma is positive for CD20 and CD79a and negative for CD5, CD10, CD23, and cyclin D1.