CD30-positive, anaplastic large-cell lymphomas that express CD15 but lack CD45. A possible diagnostic pitfall.

We report the immunohistochemical and clinical features of two cases of morphologically typical anaplastic large-cell lymphoma. One patient had lymph node and focal visceral involvement, and the other patient had multiple-organ involvement by lymphoma. In both cases, the lymphoma cells were CD30 (Ber-H2) and CD15 (Leu-M1) positive and CD45 (common leukocyte antigen) negative--a phenotype that is commonly seen in Hodgkin's disease. This unusual phenotype in large-cell anaplastic lymphoma led to an initial misinterpretation in one of the cases. Large-cell anaplastic lymphomas are highly variable, both in immunophenotype and clinical presentation. Because of this variability, a broad immunophenotypic panel, in conjunction with morphological features, should be used to establish the correct diagnosis.