Transformation of Grade I Follicular Lymphoma to Anaplastic Large Cell Lymphoma CD30+ ALK1- with Complete Response to Brentuximab Vedotin and High-Dose Methotrexate.

Lymphomas are a heterogeneous group of diseases that encompass malignant disorders of B-cells, T-cells, or natural killer cells. B-cell lymphomas represent approximately 80-85% of cases. Transformation of B-cell lymphomas from a low grade to a higher grade within the same lineage is a well-described phenomenon. The most common and well-known transformation is from follicular lymphoma to diffuse large B-cell lymphoma. However, the transformation of B-cell lymphomas to T-cell lymphomas is extremely rare. In this article, we report a case of grade I follicular lymphoma (B-cell lymphoma) that transformed into anaplastic large cell lymphoma CD30+ ALK1- (T-cell lymphoma). This article reported a case with a unique particular combination of morphology and immunophenotype in the same patient. In addition, we report a remarkable response with complete remission following treatment with Brentuximab vedotin (anti-CD30 antibody-drug conjugate) and high-dose methotrexate. The patient achieved this durable response despite the aggressive presentation.