Anaplastic large cell lymphoma (ORPHA:98841)
A rare and aggressive peripheral T-cell non-Hodgkin lymphoma, belonging to the group of CD30-positive lymphoproliferative disorders, which affects lymph nodes and extranodal sites. It is comprised of two sub-types, based on the expression of a protein called anaplastic lymphoma kinase (ALK): ALK positive and ALK negative ALCL.
Epidemiology
ALCL accounts for approximately 3% of adult non-Hodgkin lymphomas and 10% to 20% of childhood lymphomas. Its prevalence is unknown. The ALK positive subtype usually affects children and young adults. The ALK negative subtype is more commonly found in older patients over the age of 40.
Clinical description
ALCL is characterized by peripheral, mediastinal, or abdominal lymph node involvement. It manifests with the development of painless and enlarged lymph nodes, especially in the neck or armpit (axillary lymph nodes). General symptoms include loss of appetite and fatigue as well as fever, weight loss, and night sweats (B symptoms). Mediastinal involvement manifests as cough, dypsnea and/or edema. ALCL can also extend to extranodal sites such as the bones, bone marrow, subcutaneous tissue, lungs, spleen and liver.
Etiology
Etiology is unknown. In the ALK positive sub-type, the anaplastic lymphoma receptor tyrosine kinase ALK gene (2p23) is overexpressed due to a t(2;5)(p23;q35) translocation.
Diagnostic methods
Diagnosis is based on physical examination, medical history and is confirmed by histopathological and immunohistochemical evaluation of a lymph node biopsy. The biopsy shows a cohesive growth pattern, usually with lymph node-sinus involvement, with anaplastic cytology (atypical large cells with abundant cytoplasm, prominent nucleoli, and horseshoe-like or reniform nuclei), constant membrane expression of the CD30 antigen, EMA (epithelial membrane antigen) expression in the majority of cases, and CD3, CD5 or CD2 expression (mostly in ALK negative cases). ALK protein is detected by immunohistochemistry in the ALK positive sub-type. Additional tests include blood and bone marrow analysis, as well as imagery (X rays, computed tomography, PET scans and MRI) for bone disease.
Differential diagnosis
Differential diagnosis includes Hodgkin lymphoma and peripheral T cell lymphomas (see these terms), which may express CD30.
Management and treatment
Anthracycline-based chemotherapy, such as CHOP (cyclophosphamide, doxorubicin, vincristine and prednisone) or CHOP-like regimens, constitutes the first-line of treatment. It may only be combined with radiotherapy in stage I/II disease. Pediatric patients have distinct protocols similar to protocols used for B-cell lymphomas, with other drugs such methotrexate, etoposide, and cytarabine being used. High-dose chemotherapy followed by autologous stem cell transplantation can also be performed, usually in cases of relapse or as first line treatment in cases with an adverse prognosis. Antibody-drug conjugate therapy (brentuximab velotin) may be given when at least one chemotherapy regimen is unsuccesful.
Prognosis
With treatment, ALK-positive patients (5-year survival of 70-80%) have a better prognosis than ALK-negative patients (5-year survival of 33-49%). Relapse confers a poorer prognosis.

                            Last update: 
                            March 2014


                            - Expert reviewer(s): 
                            Dr Pauline BRICE