2. A 75-year-old man complained to his general practitioner (GP) about his recent weight loss and bone pain. Although a non-smoker, he has had several recent chest infections and has become increasingly short of breath on exertion. Routine biochemistry tests have been carried out and reveal that he has an increase in both his total protein and globulin protein fractions. This has prompted serum protein electrophoresis (SPEhaematology and biochemistry) of his sample which has revealed a monoclonal band in the mid-gamma region
Based on this limited information:
(a)  Carefully consider the differential diagnoses that need attention when a patient is found to have a monoclonal band in their blood plasma, and the pathological process by which they arise. (30 marks)

(b)  Clarify how additional tests (from both haematology and biochemistry) are essential to distinguish the cause and elicit the correct diagnosis for the patient, and how this would impact the treatment they would need to receive. (70 marks)