Invasive pulmonary mucormycosis: rare presentation with pulmonary eosinophilia

BACKGROUND Fungi can cause a variety of infectious diseases, including invasive mycosis and non-invasive mycosis, as well as allergic diseases. The different forms of mycosis usually have been described as mutually exclusive, independent entities, with few descriptions of overlapping cases. Here, we describe the first reported case of a patient with the complication of pulmonary eosinophilia in the course of invasive mucormycosis. CASE PRESENTATION A 74-year-old Japanese man with asthma-COPD overlap underwent emergency surgery for a ruptured abdominal aortic aneurysm. The surgery was successful, but fever and worsening dyspnea appeared and continued from postoperative day (POD) 10. A complete blood count showed leukocytosis with neutrophilia and eosinophilia, and the chest X-ray showed consolidation of the left upper lung at POD 15. We suspected nosocomial pneumonia together with an exacerbation of the asthma-COPD overlap, and both antibiotics and bronchodilator therapy were initiated. However, the symptoms, eosinophilia and imaging findings deteriorated. We then performed a bronchoscopy, and bronchoalveolar lavage (BAL) fluid analysis revealed an increased percentage of eosinophils (82% of whole cells) as well as filamentous fungi. We first suspected that this was a case of allergic bronchopulmonary mycosis (ABPM) caused by Aspergillus infection and began corticosteroid therapy with an intravenous administration of voriconazole at POD 27. However, the fungal culture examination of the BAL fluid revealed mucormycetes, which were later identified as Cunninghamella bertholletiae by PCR and DNA sequencing. We then switched the antifungal agent to liposomal amphotericin B for the treatment of the pulmonary mucormycosis at POD 29. Despite replacing voriconazole with liposomal amphotericin B, the patient developed septic shock and died at POD 39. The autopsy revealed that filamentous fungi had invaded the lung, heart, thyroid glands, kidneys, and spleen, suggesting that disseminated mucormycosis had occurred. CONCLUSIONS We describe the first reported case of pulmonary mucormycosis with pulmonary eosinophilia caused by Cunninghamella bertholletiae, which resulted in disseminated mucormycosis. Although it is a rather rare case, two important conclusions can be drawn: i) mycosis can simultaneously cause both invasive infection and a host allergic reaction, and ii) Cunninghamella bertholletiae rarely infects immunocompetent patients.