**Question:** Bone scan in multiple myeloma shows –

A. Increased uptake in areas of bone marrow involvement
B. Decreased uptake due to bone destruction
C. Increased uptake in areas of bone marrow involvement and destruction
D. Decreased uptake due to hyperostosis (thickening of bones)

**Correct Answer:** A. Increased uptake in areas of bone marrow involvement

**Core Concept:** In multiple myeloma, a type of blood cancer, there is abnormal proliferation of plasma cells in the bone marrow. This leads to bone marrow involvement, which causes increased uptake on a bone scan.

**Why the Correct Answer is Right:** Bone scans involve the administration of a radiopharmaceutical agent, typically technetium-99m methylene diphosphonate, which accumulates in areas of increased bone activity or resorption. In the context of multiple myeloma, increased uptake occurs due to the presence of plasma cell infiltration and active bone remodeling. These plasma cells produce monoclonal immunoglobulins, leading to increased bone resorption and subsequent uptake in the bone scan.

**Why Each Wrong Option is Incorrect:**

**Option A:** While areas of bone marrow involvement are indeed increased, the distinction between involvement and destruction is crucial. Destruction results in decreased uptake due to bone resorption, which is addressed by option D.

**Option B:** Decreased uptake due to bone destruction (option D) is a separate phenomenon that occurs in response to bone marrow involvement and active bone resorption in multiple myeloma.

**Option C:** Combining involvement and destruction in a single option is incorrect as it does not accurately reflect the distinct processes occurring in a bone scan of a patient with multiple myeloma.

**Option D:** Hyperostosis (thickening of bones) is a different clinical manifestation of multiple myeloma and does not reflect the findings in a bone scan. Hyperostosis would be evident on plain radiographs but not on a bone scan.

**Clinical Pearl:** In multiple myeloma, bone scans are essential for identifying areas of bone marrow involvement and active bone resorption. This information is crucial for clinical decision-making, including planning treatment modalities and assessing response to therapy.