Image Description
Pulmonary MALT Lymphoma - Immunophenotype: The immunophenotypic profile of pulmonary MALT lymphomas is similar to that seen in other locations. The neoplastic cells are CD19+, CD20+ (shown here), and CD79a+ and do not express CD5, CD10, CD23, TdT, cyclinD1 or bcl-6. About 50% of cases show aberrant CD43 expression in B cells which is an indication of neoplastic phenotype.
Bcl-10 is expressed and this correlates with the presence of t(11;18)(q21;q21) translocation resulting in fusion of BIRC3 (formerly known as API2) and MALT1 genes. There are expanded follicular dendritic cell meshworks that can be visualized with CD21, CD23, and CD35 immunostains. These meshworks are often colonized and disrupted by the neoplastic cells.
The diagnosis of MALT lymphoma is suggested by morphology in most cases. Immunostains can be difficult to interpret. Flow cytometry and/or molecular analysis is usually necessary to demonstrate a monoclonal B-cell population.
Bcl-10 is expressed and this correlates with the presence of t(11;18)(q21;q21) translocation resulting in fusion of BIRC3 (formerly known as API2) and MALT1 genes. There are expanded follicular dendritic cell meshworks that can be visualized with CD21, CD23, and CD35 immunostains. These meshworks are often colonized and disrupted by the neoplastic cells.
The diagnosis of MALT lymphoma is suggested by morphology in most cases. Immunostains can be difficult to interpret. Flow cytometry and/or molecular analysis is usually necessary to demonstrate a monoclonal B-cell population.