**Core Concept**
Smoldering myeloma, also known as asymptomatic myeloma, is a pre-malignant condition characterized by the presence of monoclonal plasma cells in the bone marrow without clinical symptoms or end-organ damage. It is a precursor to symptomatic multiple myeloma and requires close monitoring.

**Why the Correct Answer is Right**
Smoldering myeloma is defined by the presence of 10% to 59% monoclonal plasma cells in the bone marrow and either a serum M-protein level of 3 g/dL or higher, or the presence of lytic bone lesions. The condition is often asymptomatic, but regular monitoring is essential to prevent progression to symptomatic multiple myeloma. The underlying pathophysiology involves the accumulation of malignant plasma cells in the bone marrow, leading to an imbalance in normal bone marrow function.

**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect, as smoldering myeloma is characterized by the absence of clinical symptoms and end-organ damage, not the presence of kidney failure or anemia.
**Option B:** Incorrect, as smoldering myeloma does not typically present with a high serum calcium level or lytic bone lesions, which are more characteristic of symptomatic multiple myeloma.
**Option C:** Incorrect, as smoldering myeloma is defined by the presence of monoclonal plasma cells in the bone marrow, not the absence of these cells.

**Clinical Pearl / High-Yield Fact**
Smoldering myeloma often progresses to symptomatic multiple myeloma over time, emphasizing the need for regular monitoring and early intervention to prevent disease progression.

**Correct Answer: C. Smoldering myeloma is characterized by the presence of monoclonal plasma cells in the bone marrow.**