A 79-year-old female patient with prior cerebral infarction on the left basal ganglia admitted for an unveiled unruptured aneurysm on the right superior cerebellar artery (SCA), which was found on magnetic resonance imaging (MRI). She had taken an aspirin (100 mg/d) and atorvastatin (40 mg/d) since the occurrence of cerebral infarction as well as amlodipine (5 mg/d) and telmisartan (40 mg/d) for hypertension and metformin (1700 mg/d) for type 2 diabetes mellitus. There was neither history of autoimmune-related disease nor abnormal allergic reactions in her past medical history. Also, she had never smoked in her life.
Cerebral angiography displayed a small SCA aneurysm that had a broad neck with a maximum diameter of 2.62 mm and a neck diameter of 2.73 mm. Besides, it revealed a considerably narrowed vasculature on both anterior cerebral arteries (ACA), which can lead to a large territory infarction. Because the unruptured SCA aneurysm was small and unlikely to rupture, it was determined to be followed with periodical brain imaging. For disclosed severe stenosis on the ACA, she started taking the dual antiplatelet drug consisted of aspirin (100 mg/d) and clopidogrel (75 mg/d).
Two weeks later, she was readmitted to the hospital due to dyspnea that started 3 days prior. She complained of anorexia, nausea, dyspnea on exertion, and chest pain. The patient did not complain of cough, sputum, rhinorrhea, or chills. At the time of admission, she was hypoxic (pulse oximetry, 91% on room air), and a chest x-ray revealed features of bilateral infiltration after comparison to a chest x-ray obtained at the previous hospitalization (Fig. 1A, 1B). The patient’s initial vital signs were as follows: blood pressure, 136/66 mmHg; pulse rate, 78 beats/min; respiratory rate, 20 breaths/min; and body temperature, 36.7°C. The initial arterial blood gas analysis revealed pH 7.422, PaCO2 38.3 mmHg, PaO2 57 mmHg, SaO2 88.1% (2 L/min of oxygen with nasal prong), and laboratory tests showed the following: hemoglobin, 11.5 g/dL; white blood cell count, 7,410 cells/µL (neutrophils, 65.1%; lymphocytes, 24.3%; monocytes, 9.0%; eosinophils, 0.9%; and basophils, 0.7%); platelet count, 327,000 cells/µL; and C-reactive protein, 1.6mg/dL. The other serum biochemistry results were within normal limits as follow: aspartate aminotransferase, 19 IU/L; alanine aminotransferase, 5 IU/L; total bilirubin, 0.7 mg/dL; alkaline phosphatase, 59 IU/L; total protein, 7.0 g/dL; albumin, 3.5 g/dL; blood urea nitrogen, 7 mg/dL; and creatinine, 0.57 mg/dL. Congestive heart failure was excluded by normal ultrasound cardiography results and a normal level of serum brain natriuretic peptide.
Empirical antibiotics (piperacillin/tazobactam 4.5g every six hours plus levofloxacin 75mg every 24 hours) were started after bacterial cultures were obtained because bacterial pneumonia could not be ruled out on the chest x-rays. Enhanced chest computed tomography (CT) revealed symmetric peribronchial ground glass opacity (GGO) with reticulation in both lungs (Fig. 1C, 1D).
On the second day of hospitalization, the patient experienced a transient fever (37.8°C). In addition, oxygen saturation could not be maintained via nasal prong 5L/min, so we supplied oxygen via high flow nasal cannula (Flow 30L/min, FiO2 35%). On hospital day 4, bronchoalveolar lavage (BAL) was performed to rule out diffuse alveolar hemorrhage and atypical pneumonia. Bacterial polymerase chain reaction (PCR), viral PCR, Cytomegalovirus PCR, Pneumocystis jirovecii PCR, fungal culture, and acid-fast bacilli smear were performed with the BAL specimens. BAL revealed a clear color fluid, and no microorganisms were detected from any of the examinations. The patient’s clinical symptoms continued to deteriorate.
One day after BAL (day 5) and after ruling out all other possible causes of her symptoms, we suspected clopidogrel-associated interstitial pneumonitis. We changed superpirin to aspirin and initiated treatment with 1mg/kg/day of intravenous methylprednisolone. The patient’s clinical signs and chest x-ray improved after withdraw of clopidogrel and addition of steroid treatment (Fig. 2A). The patient was discharged on the 21st day of hospitalization with oral prednisolone 25mg/day. The oral steroid was tapered over a period of 6 months in the outpatient setting. A follow-up chest x-ray taken 6 months after discontinuation of steroids showed no recurrence, and the patient is currently doing well in daily life (Fig. 2B).