Final answer:
The patient assessment finding that requires the most rapid action by the nurse in a patient receiving combination treatment with rituximab (Rituxan) and chemotherapy for non-Hodgkin's lymphoma is lip swelling.
Step-by-step explanation:
The patient assessment finding that requires the most rapid action by the nurse in a patient receiving combination treatment with rituximab (Rituxan) and chemotherapy for non-Hodgkin's lymphoma is lip swelling. Lip swelling may indicate a severe allergic reaction known as anaphylaxis, which can be life-threatening. Immediate action should be taken to ensure the patient's safety.