Anaplastic lymphoma kinase-positive large B-cell lymphoma: Unusual clinical and immunophenotypic features

Anaplastic lymphoma kinase (ALK)-positive large B-cell lymphoma (ALK+ LBCL) is a rare subtype of diffuse large B-cell lymphoma. It is characterized by plasmacytic differentiation and cytoplasmic ALK positivity. Immunophenotype of ALK+ LBCL defines the terminally differentiated B-lineage cell characterized by the absence of B-cell antigens and expression of antigen associated with plasma cell differentiation. It is characterized by an aggressive behavior and poor response to standard chemotherapy. Advanced clinical stage and extranodal disease are associated with worse survival. We present a very rare case of ALK+ LBCL in a young immunocompetent lady who presented with multiple subcutaneous nodules and discuss the role of flow cytometry for prompt and accurate confirmation of the diagnosis.