A 26 year-old-male with nil significant past medical history presented to us with swelling of left lower limb since 2 weeks. He has tachyapnea and tachycardia. His JVP was normal and cardiac auscultation was normal. Examination was suggestive of deep vein thrombosis (DVT) of the left lower limb. Doppler of lower limb confirmed this and patient was appropriately placed on anti-coagulation. He had persistently elevated blood eosinophil counts. Bone marrow biopsy was and mutational analysis confirmed presence of lymphocytic variant of hypereosinophilic syndrome (HES). He continued to have tachycardia and cardiac enzymes were positive. Electrocardiogram revealed sinus tachycardia and echo was normal. After ruling out the possibility of pulmonary thromboembolism with CT pulmonary angiogram, myocarditis was attributed to HES. He was promptly treated glucocorticoids which were later tapered gradually in lieu of improvement of his clinical condition and declining eosinophil counts. He was discharged and was under regular follow-up.
Key words: Hypereosinophilic syndrome, Persistent eosinophilia, Deep vein thrombosis, Myocarditis.