A 63-year-old man develops acute respiratory failure after autologous stem cell transplant for lymphoma. His initial posttransplant course was notable for mucositis. Approximately 2.5 weeks posttransplant, following count recovery, he develops a dry cough and worsening arterial hypoxemia. Chest CT reveals diffuse ground glass opacities, and he is transferred to the ICU, given diuretics, and placed on high flow nasal cannula oxygen and broad-spectrum antibiotics. On ICU day 2 he is intubated for worsening work of breathing and fatigue. Bronchosopy is unremarkable, and microbiologic studies of BAL including respiratory viral PCR are unrevealing. His ventilatory settings escalate despite low-tidal volume ventilation, and after another week of mechanical ventilation, his course is complicated by multiorgan failure. Care is transitioned to comfort measures only.
Which of the following is the most likely diagnosis?A. Invasive pulmonary aspergillosis (IPA)
Correct Answer: C
Idiopathic pneumonia syndrome is a dreaded complication of hematopoietic stem cell transplantation, defined as diffuse alveolar injury in the absence of evidence of respiratory tract infection. Although the pathogenesis remains unclear, it is thought most likely to be an inflammatory reaction to the pre-transplant conditioning regimen, which may involve high-dose chemotherapy and radiotherapy. Differential considerations include viral pneumonia and diffuse alveolar hemorrhage. Many clinicians administer high-dose steroids; etanercept (TNF-alpha inhibitor) has also been studied, though no high quality evidence exists to support either treatment and the prognosis remains very poor. This patient had an autologous stem cell transplant and so cannot have developed GVHD. Infectious causes are possible despite the negative workup (eg, a viral pathogen not tested for with multiplex PCR), but fungal and bacterial infections are unlikely given the imaging and unrevealing BAL.