The discovery of HAVCR2 mutations in inflammatory conditions is a prime example how better understanding of the molecular basis of HLH can lead to treatment optimization, as shown by promising responses following immunomodulatory treatment with the JAK1/2 inhibitor ruxolitinib in SPTCL and patients with lupus panniculitis [159, 160]. The gene discussed is HAVCR2; the disease is subcutaneous panniculitis-like T-cell lymphoma.