Frequency and age at diagnosis of “diagnosis code-based possible malignancy-associated HLH” in patients with hematological malignancies (n = 222) and of all hematological malignancies in Sweden from 2012 to 2018 (n = 35 117). (A) Number of patients with “diagnosis code-based possible malignancy-associated HLH” from 2012 to 2018 with an underlying hematological malignancy (bar chart with y-axis to the left) in relation to the total number of hematological malignancies in Sweden from 2012 to 2018 (line chart with y-axis to the right). All individuals are divided into age groups of 5 years (x-axis); males are depicted as blue and females as orange. (B) Proportion of patients with hematological malignancies in Sweden from 2012 to 2018 that have “diagnosis code-based possible malignancy-associated HLH.” Individuals are divided into age groups of 5 years (x-axis); males are depicted with blue, females with orange, and both sexes with green bars.