Diagnosis and prognosis of acute respiratory distress syndrome related to diffuse pneumonic-type adenocarcinoma: a single-center case series study

Background: The absence of diagnosis of acute respiratory distress syndrome (ARDS) concerns 20% of cancer patients and is associated with poorer outcomes. Diffuse pneumonic-type adenocarcinoma (P-ADC) is part of these difficult-to-diagnose ARDS, but only limited data are available regarding critically ill patients with diffuse P-ADC. We sought to describe the diagnosis process and the prognosis of P-ADC related ARDS patients admitted to the intensive care unit (ICU). Methods: Single-center observational case series study. All consecutive patients admitted to the ICU over a two-decade period presenting with (I) histologically or cytologically proven adenocarcinoma of the lung and (II) ARDS according to Berlin definition were included. Clinical, biological, radiological and cytological features of P-ADC were collected to identify diagnostic clues. Multivariate logistic regression analyses were performed to assess factors associated with ICU and hospital mortality. Results: Among the 24 patients included [70 (61-75) years old, 17 (71%) males], the cancer diagnosis was performed during the ICU stay in 19 (79%), and 17 (71%) required mechanical ventilation. The time between the first symptoms and the diagnosis of P-ADC was 210 days (92-246 days). A non-resolving pneumonia after 2 (2 to 3) antibiotics lines observed in 23 (96%) patients with a 34 mg/L (19 to 75 mg/L) plasma C-reactive protein level at ICU admission. Progressive dyspnea, bronchorrhea, salty expectoration, fissural bulging and compressed bronchi and vessels were present in 100%, 83%, 69%, 57% and 43% of cases. Cytological examination of sputum or broncho-alveolar lavage provided a 75% diagnostic yield. The ICU and hospital mortality rates were 25% and 63%, respectively. The time (in days) between first symptoms and diagnosis [odds ratio (OR) 1.02, 95% confidence interval (95% CI): 1.00-1.03, P=0.046] and the Simplified Acute Physiology Score II (OR 1.16, 95% CI: 1.01-1.33, P=0.040) were independently associated with ICU mortality. Conclusions: Non-resolving pneumonia after several antibiotics lines without inflammatory syndrome, associated with progressive dyspnea, salty bronchorrhea, and lobar swelling (i.e., fissural bulging, compressed bronchi and vessels) were suggestive of P-ADC. Delayed diagnosis of diffuse P-ADC seemed an independent prognostic predictor and disease timely recognition may contribute to prognosis improvement.