gms | German Medical Science

Introduction: Rhizopus is a common saprobic fungus, found on organic substrates. Opportunistic zygomycosis occurs with diabetic ketoacidosis, haematological malignancies, or severe immunosuppression.

Background: A 63-year-old male with diabetes mellitus (DM) and prostate cancer developed squamous-cell carcinoma of the left (LUL) and right upper lobes (RUL). After 4 cycles of radio-chemotherapy he underwent interval VATS for atypical RUL wedge-resection and LUL cuff resection. On post-operative day (POD) 2 acute respiratory failure due to total occlusion of the left pulmonary artery prompted left pneumonectomy. Due to diffuse oozing the chest was packed with 11 laparotomy sponges. Worsening septic shock required maximal vasopressor support. On POD 5 the chest was de-packed, irrigated with povidon-iodine and closed. Cultures from pericardium, chest and sputum remained sterile. Blood cultures grew Staph. epidermidis and antibiosis was broadened. A chest tube drained black fluid positive for 2 different Rhizopus species (R. microsporus and azygosporus). IV posaconazole and liposomal amphotericin B were initiated. The chest was frequently rinsed with saline. On POD 8 necrosis of the incision was noted. Within days the necrosis expanded to a palm sized area. Samples revealed generalized invasive zygomycosis. Extensive debridement of pericardium, pleura and chest wall with resection of 4 rips was performed. Invasion of the aorta, heart and bronchus stump could not be excised. Following the family opted for comfort-care and the patient expired.

Results: This case represents the fatal outcome of Rhizopus infection originating and hiding in the chest after pneumonectomy. Our patient expressed no typical risk factors. Immunocompromise due to repeat surgery, bacteremia and radio-chemotherapy might have been present but DM was controlled. The source of infection remains unclear. The chest cavity offered ideal environment for this aggressive opportunistic mold and invasion was only noted when outgrowing from surgical incision. Hallmark of zygomycosis is vascular invasion and tissue necrosis, which occurred rapidly despite IV combination antimycotic therapy. At surgical intervention, the large vessels and heart had already been invaded.

Conclusion: We reinforce the need for early removal of chest packing, awareness of invasive zygomycosis, timely diagnostic tap with fungal stains and recommend local irrigation with amphotericin B after early radical surgical debridement.

Image 1: A B: HE stain of tissue with Rhizopus spores, C: PAS-stain of tissue with Rhizopus spores, D: wound necrosis, E F: surgical resection of Rhizopus invasion