This question requires identifying the established diagnostic criteria for multiple myeloma.

Multiple Myeloma Diagnostic Criteria Explained

The diagnosis of multiple myeloma relies on specific clinical and laboratory findings. Let's evaluate each potential criterion:

• 1. Increased malignant plasma cells in the bone marrow: This is a fundamental criterion. A significant increase in plasma cells (typically >10%) in the bone marrow is characteristic of multiple myeloma.
• 2. Serum and/or urinary M protein: The presence of monoclonal proteins (M protein) in the blood (serum) or urine is another key diagnostic indicator. This protein is produced by the malignant plasma cells.
• 3. Skeletal lytic lesions: Multiple myeloma commonly causes damage to the bones, resulting in areas of bone destruction known as lytic lesions. These are identified through imaging studies like X-rays or CT scans.
• 4. Skeletal blastic lesions: Unlike lytic lesions, blastic lesions represent areas of abnormal bone formation. These are generally *not* a feature of multiple myeloma; myeloma predominantly causes bone *destruction* (lytic lesions).

Selecting the Correct Criteria Combination

Based on the analysis, criteria 1, 2, and 3 are established diagnostic features of multiple myeloma. Criterion 4 (skeletal blastic lesions) is incorrect.

Therefore, the correct combination includes:

• Increased malignant plasma cells in the bone marrow
• Serum and/or urinary M protein
• Skeletal lytic lesions

This corresponds to option 1, which includes items 1, 2, and 3.