Understanding Evaluation and Management of Primary Cutaneous and Systemic ALCL
June 15, 2010
Querfeld et al have written a comprehensive evaluation of primary cutaneous and systemic anaplastic large cell lymphoma (ALCL). The important similarities between them are outlined in the article, for example tumor cells expressing the CD30 antigen for both subtypes. In addition, important differences such as the wide spectrum of CD30+ lymphoproliferative disorders of the skin and the large differences in outcomes of the primary cutaneous vs systemic types of ALCL are discussed. Other important differences include expression of the anaplastic lymphoma kinase (ALK) protein. The ALK protein is activated most frequently through the nonrandom t(2;5) chromosome translocation, resulting in fusion of the nucleophosim (NPM) gene located at 5q35 to 2p23 and encoding the receptor tyrosine kinase, ALK. Most patients with primary cutaneous ALCL are ALK-negative, yet their 5-year disease-free survival rate is > 90%. Systemic ALCL is divided into ALK-positive and ALK-negative cases. Patients with systemic ALCL that is ALK-positive have a much higher 5-year survival rate of 70%, compared with a rate of 49% for those with systemic ALCL that is ALK-negative.