HES/Sjögrens, AOSD flare, HLH testing, chronic lymphocytic leukemia, morphea, FMF, bilateral hygroma, polyarthralgia, AOSD/FMF, Jak2+Cytosis, Jak2+ myeloproliferative syndrome, chemotherapy-induced fever, Castleman’s? This evidence concerns the gene JAK2 and cystic hygroma.