Table 5.

Main differential diagnosis and clinical characteristics for CRS.

Differential Diagnosis	Clinical Characteristics
Sepsis	Sepsis can cause fever, hypotension, and respiratory complications. The evaluation for infection should include adequate microbiological diagnostics including blood cultures. It will often be necessary to initiate empirical antibiotic therapy.
Disease progression	Rapid progression of underlying malignancy can cause fever and a clinical, metabolic image similar to CRS.
Tumor lysis syndrome	The direct decay of malignant cells, especially in lymphoid malignancies, can cause metabolic disorders, with laboratory and clinical findings similar to CRS.
Heart failure	Cardiac failure due to cardiomyopathy, ischemic heart disease or pericardial effusion, may produce a clinical picture with respiratory failure as in severe CRS.
Venous thromboembolism	Clinical features of pulmonary embolism (PE) and deep vein thrombosis (DVT) such as dyspnea, hypoxia, hypotension, peripheral edema and swelling in the extremities may resemble CRS. Image diagnostics for this purpose may be relevant for diagnostic clarification.
Acute respiratory distress syndrome (ARDS)	Respiratory problem is the dominant symptom, with fluid accumulation in the lung tissue that can produce characteristic radiological changes.
Allergic reaction/anaphylactic reaction	Allergic reactions including severe drug reactions can cause fever, rash, capillary leakage and dyspnea. An overview of recent changes in the drug regimen should therefore be reviewed in case of suspected CRS.
Hemophagocytic lymphohistiocytosis (HLH)	HLH is a hyperinflammatory syndrome that shares common features and is likely related to CRS. Both by CRS and HLH are macrophage activation and cytokine storm.