In May 2020, during the outbreak of SARS-CoV-2 in Italy, a 23-year-old male, non-smoker, with no remote clinical history, presented to the Emergency Department; he had suffered from fever (up to 38 C), cough, and worsening shortness of breath for 3 days. At clinical examination, the most important clinical feature was bilateral wheezing; nevertheless, the patient did not have a history of asthma nor chronic sinusitis with nasal polyposis. During the visit, the patient did not refer to new smoking or second hand smoke habit, nor drugs or new antigen exposures.
Blood test showed an increase in peripheral blood eosinophilia (1.8x1,000/muL, 12.5% of the total leukocyte number) with leukocytosis (14.45x1,000/muL); in particular, neutrophils were 61.6% (8.91x1,000/muL), lymphocytes were 17.7 (2.56x1,000/muL), monocytes 7.6% (1.1x1,000/muL), and basophils were 0.6% (1.8x1,000/muL). A mild elevated C-reactive protein (CRP=1.53 mg/dL) was found, with negative procalcitonin, mild elevated Lactate dehydrogenase (LDH 384 U/L), mild elevated Interleukin-6 (IL-6=12.4 pg/mL), and negative D-dimer (230 ng/mL). Arterial blood gases showed: pH=7.39; pO2=59 mmHg; pCO2=40 mmHg; HCO3=25 mmol/l with a fraction of inspired oxygen of 35% in Venturi mask and arterial oxygen pressure on fraction of inspired oxygen ratio (PaO2/FiO2) of 168. Due to the persistence of respiratory symptoms and respiratory failure, the patient underwent a chest high-resolution CT scan, which reveal bilateral GGO localized in the upper left lobe (in particular in lingular segment) and in the right lower lobe (Figure 1).
For these reasons, he was hospitalized with suspected COVID-19 in the Infectious Diseases Unit in Santa Maria Nuova Hospital of Reggio Emilia.
As of the chest CT, the suspicious of COVID-19 was high, but we had to consider other possibilities in differential diagnosis, such as eosinophilic granulomatosis with polyangiitis (EGPA), alveolar hemorrhage, AEP, parasitic pneumonia, drug toxicity, or toxic inhalants.
In the Infectious Diseases Unit, on day one the patient was tested negative with nasopharyngeal swab for SARS-CoV-2, and the result was confirmed after 24 hours with a second nasopharyngeal swab that was negative as well. Moreover, serology test for SARS-CoV-2 was also negative.
In order to exclude a vasculitis, antineutrophil cytoplasmic antibodies (ANCA) were searched, and resulted asnegative.
After 24 hours from admission in hospital, patient's respiratory conditions worsened with symptoms such as dyspnea and increase in respiratory rate (25 breaths per minute), so high flow oxygen therapy with a fraction of inspired oxygen of 60% was needed.
A therapy with two daily inhalations formoterol/beclomethasone metered-dose inhaler 100/6 mug was introduced to improve respiratory symptoms, with only partial improvement of symptoms.
In consideration of the increase in peripheral blood eosinophilia and bilateral GGO on chest CT, a flexible bronchoscopy with bronchoalveolar lavage (BAL) was performed; an amount of 150 mL of physiological liquid was introduced to perform BAL and 70 mL of clear liquid was collected, with no traces of blood in it. BAL revealed eosinophils alveolitis (40%) and mucous secretion with no evidence of bacteria or viruses, SARS-CoV-2 included. These findings were compatible with AEP (Figure 2). For this reason, we started a therapy with oral corticosteroid (prednisone 50 mg daily), with a rapid clinical improvement and no more fever.
After 1 week of therapy, the initial respiratory failure was resolved and blood tests revealed a lower peripheral blood eosinophilia. The prednisone dose was halved in 14 days, and the patient was discharged with the dose of 25 mg. Before the discharging we obtained the informed consent for the publication of this case report.