Diagnostic utility of immunohistochemistry in a case of anaplastic large cell lymphoma (small cell variant)

In young patients with lymphadenopathy in whom a diagnosis of lymphoma is considered, immunohistochemical analysis is a valuable part of the diagnostic armamentarium. This technique is especially important for cases in which the morphologic features do not allow for accurate subtyping of the disease entity. One disease that was defined on the basis of a unique immunophenotype is anaplastic large cell lymphoma (ALCL), an entity that is often considered in the differential diagnosis of Hodgkin lymphoma. This case illustrates the utility of immunohistochemical markers in establishing the diagnosis of anaplastic large cell lymphoma.