WHO classifies these infiltrates into 5 patterns: a Common Pattern consisting of large variably-shaped cells with large nuclei that typically contain multiple nucleoli (60–70% of cases); a Small Cell Pattern consisting of small to medium-sized neoplastic cells with clear cytoplasm and "hallmark" cells that are concentrated around small blood vessels (5–10% of cases); a Lymphohistiocytic Pattern consisting of small neoplastic cells along with abundant histiocytes (10% of cases); a Hodgkins-Like Pattern in which the architecture resembles the nodular sclerosis pattern of Hodgkin lymphoma (3% of cases); and a Composite Pattern consisting of two or more of the just described patterns (15% of cases). Detection of circulating autoantibody against ALK supports the diagnosis. Individuals with low levels of these autoantibodies are at an increase risk of relapsing after treatment. Gene and molecular abnormalities
In 80–85% of cases, the ALK detected in ALK-positive ALCL is a NPM1-ALK fusion protein. It is made by a fusion of NPM1 gene, which makes nucleophosmin 1, located on the long or "q" arm of chromosome 5 at position 35 (notated as 5q35) with the ALK gene located on the short or "p" arm of chromosome 2 at position 23 (notated as 2p23) to form a chimeric gene notated as (2;5)(p23;q35). In 13% of cases ALK fuses with the TPM3 gene or in <1% of cases for each of the following genes: TFG, ATIC, CLTC, TPM4, MSN, RNF213 (also termed ALO17), MYH9, or TRAF1.
gemcitabine, dexamethasone, and cisplatin), DHAP, and ICE.Drugs that inhibit ALK activity such as crizotinib and alectinib have been successful in establishing complete and partial remissions in a limited number of patients with advanced, refractory ALK-positive ALCL. These and other drugs are undergoing clinical trials to determine there safety and effectiveness in treating ALK-positive ALCL. (Also see clinical trials that use ALK inhibitors in ALK-positive ALCL and clinical trials that use ALK inhibitors in ALK-positive cancers.) ALK-negative anaplastic large cell lymphoma
Signs and symptoms
Unlike ALK-positive ALCL, ALK-negative ALCL tends to occur in older adults (median age at diagnosis: 55–60 years) and presents primarily with lymph node involvement; only 20% of patients with ALK-ALCL present with extra-nodal disease in sites such as the skin, bone, and soft tissues. Nonetheless, most individuals (~67%) present with advanced stage grade III or IV disease in which neoplastic infiltrates occur in multiple lymph node locations and/or extra-nodal sites. ALK autoantibodies are not found in this type of ALCL. The prognosis of ALK-negative ALCL is often quoted as being worse than that for ALK-positive ALCL but this may reflect the older age and advanced stage at which ALK-negative disease presents: studies comparing age- and grade-matched ALK-positive to ALK-negative ALCL patients show little differences in prognoses. Diagnosis
The histology of ALK-negative ALCL, similar to ALK-positive ALCL, consist of "hallmark" cells that strongly express CD30. Unlike ALK-positive ALCL, however, ALK-negative ALC does not fall into different morphological patterns.