In this case, the patient had experienced progressive fatigue, dyspnea, and thrombocytosis over the preceding month, leading her hematologist to initiate ruxolitinib, a JAK1/2 inhibitor, as second-line therapy. Overall, this case illustrates the need for both diagnostic vigilance and collaborative treatment strategies in addressing the less common but serious venous manifestations of ET. Here, JAK1 is linked to Thrombocytosis.