1. Most Likely Diagnosis and Why? The chest X-ray shows bilateral diffuse alveolar infiltrates with perihilar and lower lung zone predominance, a hazy “bat-wing” appearance, and relative sparing of the peripheral lung zones. The cardiac silhouette is obscured by the opacity (suggesting some degree of cardiomegaly/heart failure). These findings are most suggestive of pulmonary edema (likely cardiogenic). Why: Bilateral, symmetric, central (perihilar) opacities. “Bat-wing” distribution typical of cardiogenic pulmonary edema. Increased vascular markings. Presence of lines/tubes suggests patient is critically ill. Alternatives could include ARDS, diffuse pneumonia, or alveolar hemorrhage — but the distribution and symmetry point most strongly to pulmonary edema. 2. Next Best Diagnostic Step Urgent bedside echocardiography to assess left ventricular function and rule out acute decompensated heart failure. ABG (arterial blood gas) to assess severity of hypoxemia. 3. Key Differential Diagnoses or Confirmatory Tests Acute Respiratory Distress Syndrome (ARDS): Non-cardiogenic pulmonary edema; differentiate with BNP/pro-BNP levels, echo for cardiac function. Diffuse pneumonia (e.g., viral, bacterial, PCP): Consider infection—confirm with sputum cultures, blood cultures. Pulmonary hemorrhage (e.g., vasculitis): Evaluate with bronchoscopy, hemoglobin levels, autoimmune work-up. Confirmatory tests: Echocardiography (to confirm heart failure as etiology). BNP or NT-proBNP levels (elevated in cardiogenic pulmonary edema). 4. Possible Treatment / Management If cardiogenic pulmonary edema: Supplemental oxygen, non-invasive ventilation or intubation if severe. IV diuretics (e.g., furosemide). Vasodilators (nitroglycerin) if hypertensive. Treat underlying cause (e.g., acute MI, arrhythmia, valvular disease). If ARDS: Mechanical ventilation with low tidal volume strategy. Treat underlying cause (sepsis, trauma, pancreatitis, etc.). If pneumonia: Broad-spectrum antibiotics pending culture. If pulmonary hemorrhage: Immunosuppressive therapy depending on etiology. ✅ Summary: Most likely diagnosis = cardiogenic pulmonary edema (bilateral symmetrical perihilar opacities with bat-wing pattern). Next step = Echocardiography + ABG. Differentials = ARDS, pneumonia, pulmonary hemorrhage. Management = Oxygen, diuretics, vasodilators, treat underlying cardiac cause. Would you like me to quantify the probability of each differential (cardiogenic edema vs. ARDS vs. pneumonia) based on imaging features?