We aimed to report autopsy findings in patients with acute myeloid leukemia (AML) and non-Hodgkin lymphoma (NHL) in the modern era, and also to focus on lung pathology in the subgroup of patients with acute respiratory failure (ARF) of unknown etiology, which is associated with especially high mortality rates. Charts and autopsy reports of 107 patients (59 AML and 48 NHL) autopsied between 2003 and 2018 were reviewed. More than 50% of patients had missed major diagnoses found at autopsy with 95% of lungs displaying abnormal findings. Malignant infiltration in at least one organ was observed in about 70% of patients with either no complete remission or relapse at the time of death (n = 92) versus 20% in patients without signs of active malignancy (n = 15) (p = 0.001). In patients with ARF of unknown etiology (n = 59), the proportion of malignant lung infiltration was 27% and equilibrated with bacterial pneumonias (29%), fungal pneumonias represented 8%, and isolated alveolar damage or pulmonary edema were the only findings in 32% of patients. Overall, 85% of patients with ARF of unknown etiology had either relapsed or not achieved remission at time of death and 80% of patients with malignant lung infiltration had ARF of unknown etiology. Ninety percent of malignant infiltration and fungal infections were observed in patients with no complete remission or relapse. Autopsy remains valuable in AML and NHL patients; besides infections, malignant infiltration is a significant contributor to ARF of unknown etiology and is rarely diagnosed ante mortem.
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