Anaplastic large cell lymphoma, ALK-positive

Anaplastic large cell lymphoma (ALCL), anaplastic lymphoma kinase (ALK)-positive (ALK+ ALCL) is an aggressive CD30-positive T-cell lymphoma that exhibits a chromosomal translocation involving the ALK gene and the expression of ALK protein. No particular risk factor has been clearly identified for ALCL. ALK+ ALCL shows a broad morphologic spectrum, but all cases contain a variable proportion of cells with eccentric, horseshoe- or kidney-shaped nuclei often with an eosinophilic region near the nucleus (hallmark cells). Five morphologic patterns can be recognized. ALK+ ALCL occurs in young subjects (median age ∼35 years), with male predominance, and frequently presents at an advanced stage, with systemic symptoms and extranodal involvement. Near 40% of patients are low risk according to the International Prognostic Index (IPI). Overall, the prognosis of ALK+ ALCL is remarkably better than other T-cell lymphomas. The IPI and the PIT scores in general predict survival in patients with ALK+ ALCL. Standard first-line treatment for ALK+ ALCL consists of doxorubicin-containing polychemotherapy, which is associated with an overall response rate of ∼90%, a 5-year relapse-free survival of ∼60%, and a 5-year overall survival of 70%. Excellent results have been reported with a variety of anthracycline-based chemotherapy regimens including CHOP, CHOEP or MACOP-B. Consolidative high-dose chemotherapy and autologous stem cell transplantation (HDC/ASCT) has also been evaluated in patients in first remission with favourable results, however, superiority to standard chemotherapy is unproven and this approach remains investigational. Following universally accepted guidelines for the treatment of failed aggressive lymphomas, HDC/ASCT can effectively salvage a proportion of patients with relapsed or refractory ALK+ ALCL. Recently, the development of novel therapies targeting CD30 and ALK appear promising.