A Case of Idiopathic Hypereosinophilic Syndrome Presenting With Acute Respiratory Distress Syndrome
A 37-year-old male visited the emergency department at Samsung Medical Center, Seoul, Korea, presenting with a chief complaint of dyspnea. Initial symptoms had begun 1 week prior to his visit, characterized by fever and chills, followed by progressive respiratory difficulty. He appeared acutely ill. A crackling sound was heard upon chest examination. His heartbeat was regular without a murmur. A purplish discoloration of the right ankle was observed, but there were no local heat or tenderness. Initial blood pressure was 163/91 mmHg, pulse rate was 114 beats/min, respiratory rate was 24 breaths/min, and body temperature was 38℃. Oxygen saturation was initially detected as 87%, and increased to 95% upon oxygen supplement via nasal cannula at 5 L/min. Following oxygen supplementation, arterial blood gas analysis (ABGA) showed a pH of 7.39, partial pressure of carbon dioxide (PaCO2) of 40.9 mmHg, partial pressure of oxygen (PaO2) of 113.7 mmHg, and oxygen saturation of 98%.\nLaboratory tests revealed peripheral eosinophilia and thrombocytopenia with a white blood cell count of 22,580/µL (50% neutrophils, 31% eosinophils, 10% lymphocytes), Hb levels at 13.7 g/dL, and a platelet count of 26,000/µL. Prothrombin and activated partial thromboplastin times were 15 sec, and 35.4 sec respectively. Fibrinogen levels were within the normal range, but the concentration of D-dimer was markedly elevated at 26.69 µg/mL. Serum total IgE and ECP levels (939.4 IU/mL and 201.0 ng/mL, respectively) were both elevated, too. Tests for both anti-nuclear antibodies and anti-neutrophil cytoplasmic antibodies were negative. A test for parasites in the stool and serum were negative. Bone marrow biopsy showed normal cellularity with increased eosinophils. Fip1-like1 and platelet-derived growth factor receptor alpha (FIP1L1-PDGFRA) gene fusion was not detected. Patchy consolidation with ground-glass opacity in both lower lung zones was noticed in the initial chest radiography ().\nDuring the initial workup, the patient became progressively tachypneic with increased oxygen demand to 15 L/min via facial mask. The patient was transferred to the intensive care unit and oxygen supply was increased to 100% by high-flow nasal cannula. Despite supplementation, PaO2 levels remained low (49.9 mmHg) leading to a diagnosis of ARDS, and then the patient underwent intubation and mechanical ventilation.\nBronchoalveolar lavage (BAL) revealed marked eosinophilia (187/200 evaluated cells, 93.5% eosinophils). Skin biopsy of the right ankle showed diffuse eosinophilic perivascular infiltration of the dermis () and eosinophilic abscess of subcutaneous fat (). Duplex sonography revealed deep vein thrombosis in the left popliteal, soleal, and peroneal veins. Nerve conduction test and electromyography showed neuropathy in the right posterior tibial nerve.\nA diagnosis of IHES was reached based on the presence of peripheral and tissue eosinophilia, along with the exclusion of other causes of eosinophilia. High-dose corticosteroid (methylprednisone 1 mg/kg/day) therapy was initiated on the first day of admission. By day 3, eosinophil counts decreased to the normal range (). Extubation was performed on day 4 as a result of clinical and radiological improvements.\nA chest CT scan was obtained on day 9 to evaluate symptoms of mild dyspnea despite the dramatic improvement seen by simple radiography (). Pulmonary thromboembolism (PTE) was detected in the bilateral lobar and segmental branches of the pulmonary arteries (), and we started anticoagulant therapy. On day 23, the patient was discharged from the hospital with a gradual tapering of corticosteroids.