Time relation between HLH and cancer diagnoses. (A) Frequency of patients with “diagnosis code-based possible malignancy-associated HLH” 2012 to 2018 with a date of cancer diagnosis in Swedish Cancer Register (n = 227) (y-axis) in relation to the time (years) of HLH diagnosis to the cancer diagnosis (x-axis, HLH diagnosis ranging from −4.6 years to +18.2 years from cancer diagnosis). (B) Frequency of patients with “probable malignancy-associated HLH” defined as HLH occurring within day −90 to day +365 from their cancer diagnosis between 2012 and 2018 (n = 146) in relation to the time (months) from HLH diagnosis to cancer diagnosis (x-axis). The time point zero is the diagnosis of cancer.