Apart from the age-dependent SPTCL/HLH clinical spectrum, HAVCR2 mutations can contribute to HLH/HLH-like systemic illnesses alone, or idiopathic HLH/HLH-like systemic illnesses, without evidence of SPTCL or preceding SPTCL [7, 18, 19]. The gene discussed is HAVCR2; the disease is subcutaneous panniculitis-like T-cell lymphoma.