ALK and anaplastic large cell lymphoma: Fortunately, most small cell predominant or lymphohistiocytic variants of anaplastic large-cell lymphoma are ALK+, as a diagnosis of ALK– anaplastic large-cell lymphoma with variant histology would be particularly difficult; large CD30+ hallmark type cells must be present with a preferential distribution of the CD30+ large cells around blood vessels.131 In ALK– anaplastic large-cell lymphoma with a null phenotype (and genotype), immunostains to exclude other tumours such as Hodgkin lymphoma (HL), carcinoma and acute leukaemia must be performed (Table 6).