A 58-year-old, never-smoking housewife presented to the Department of Pulmonary and Critical Care Medicine of China-Japan Friendship Hospital with the chief complaints of cough, dyspnea, and intermittent fever. She had a history of leukopenia of unknown origin that was untreated. Chest computed tomography (CT) revealed scattered solid nodules in both lungs, with a fibrous striped shadow in the medial segment of the middle lobe of the right lung and slight enlargement in the left hilum (Figure 1A). Though broad-spectrum antibiotics were administered, the patient's clinical status worsened, developing a severe pneumonia with type I respiratory failure and her pulse oximetry oxygen saturation (SpO2) decreased to 70% while on oxygen delivered at the rate of 5 L/min through a nasal cannulae. The patient was transferred to the intensive care unit (ICU) for close monitoring.
A general physical examination was performed. The patient, who was conscious, displayed the following vital signs: temperature, 38.6 C; pulse rate, 105 bpm; respiratory rate, 35 breaths/min; blood pressure, 118/77 mmHg; oxygen saturation, 93% while on oxygen delivered through a nasal cannulae at a rate of 5 L/min. Chest auscultation revealed raw breathing sounds and wet rales in both lungs. Pitting edema in both lower extremities was found as well. Results of laboratory tests were: white blood cell count 8.54*10^9/L with neutrophil predominance (89.7%); reactive protein > 200mg/L (reference value <10 mg/L); serum procalcitonin 1.67 ng/mL, alanine transaminase 48 U/L, aspartate transaminase 68 U/L. Autoimmune tests including anti-neutrophil antibody (ANA), anti-neutrophil cytoplasmic antibody (ANCA), and rheumatoid factor (RF) were negative. Results of blood culture, 1-3-beta-D-glucan (BDG) assay, galactomannan (GM) tests, T-spot, cryptococcal antigen nucleic acid, blood EB virus DNA, cytomegalovirus DNA were negative. Fiberoptic bronchoscopy with bronchoalveolar lavage (BALF) revealed extensive hyperemia and edema in the bronchial mucosa, and no other abnormalities were observed. Fungal cultures were positive for Candida albicans. Cultures for bacteria and mycobacteria were negative. All virus, Mycoplasma pneumoniae, and Chlamydia nucleic acid amplification tests were negative. No pneumocystis infection was identified and tumor cytology was negative. Contrast-enhanced chest CT revealed patchy areas of ground-glass opacities (GGO) and consolidation in both lungs scattered all over and with slightly enlarged mediastinal lymph nodes (Figure 1B).
On ICU day 2, her respiratory status continued to decline, and bedside chest radiographs (Figure 2A) showed progression of bilateral infiltrates. Mechanical ventilation (PC mode, FiO2 100%, F 35/min, PC 18 cmH2O, PEEP 10 cmH2O), and venovenous extracorporeal membrane oxygenation (V-V ECMO) were performed to maintain adequate oxyhemoglobin saturation. We delivered an almost constant flow of 6 L/min/m2 via ECMO. A bedside TBCB was performed on the same day to obtain a definitive diagnosis. Three specimens were obtained from the outer and posterior basal segments of the lower lobe of the left lung, and histological examination revealed fibroblasts intermixed with loose connective tissue and collagen in the alveoli and the distal bronchioles (Figures 3A,B). These findings were typical of OP. Thus, an OP diagnosis was established.
The following day, the patient's treatment was changed to intravenous methylprednisolone in continuous infusion, 240 mg for 3 days, followed by 80 mg for 5 days, and then 40 mg as the maintenance dose. The fever subsided the day after the steroid was given, and her general condition improved significantly. The patient was extubated 4 days after endotracheal intubation and tracheotomized for 24 days. She remained on VV-ECMO for 15 days. Systemic heparinization is required during ECMO treatment. On the one hand, thrombus formation can be seen in front of the ECMO membrane and behind the membrane, and thrombosis can be seen around the PICC tube. On the other hand, the patient developed hemoptysis several times, hematuria, hematoma of abdominal muscle successively. For hemoptysis, we did a bronchoscopy to stop the bleeding. And we adjusted the heparin pump rate according to the APTT target value to prevent massive bleeding. After the patient was withdrawn from ECMO, heparin was stopped, and the hemoptysis was gradually relieved. There was no recurrence of hematuria and no increase in abdominal hematoma. No thrombosis was found in the deep veins of the extremities.
Bedside chest radiographs showed consolidation of both lungs decreased significantly on ICU day 10 (Figure 2B). On day 21 after steroid use, her chest radiograph (Figure 1C) showed that the consolidation was less than the previous. On day 41 after steroid use, her symptoms and chest radiograph (Figure 1D) were indicative of a significant improvement, with complete resolution of pulmonary symptoms.