A Rare Case Of Alk-Positive Large B-Cell Lymphoma With Cd33 Expression

Anaplastic lymphoma kinase-positive large B-cell lymphoma (ALK+ LBCL) is a very rare and aggressive subtype of diffuse large B-cell lymphoma characterized by ALK rearrangement. Immunophenotypically, the tumor cells are typically negative for common B-cell markers, T-cell markers, and CD30; however, they express markers of terminally differentiated B cells/plasma cells such as CD38, CD138, and MUM-1/IRF4. The diagnosis of ALK+ LBCL can be challenging, and often a large panel of immunostains is required to exclude other hematopoietic and nonhematopoietic neoplasms. To date, approximately 130-140 cases have been reported, but here we report the first known case of ALK+ LBCL with unusual CD33 expression.