**Question:** All are true for multiple myeloma except -

A. Multiple myeloma is a plasma cell disorder characterized by the clonal proliferation of monoclonal plasma cells in bone marrow.
B. Symptoms of multiple myeloma often overlap with those of other hematological malignancies, making diagnosis challenging.
C. Multiple myeloma is a rare disease, affecting less than 1% of all hematological malignancies.
D. Treatment options for multiple myeloma have improved significantly in recent years, leading to better prognosis.

**Correct Answer: C. Multiple myeloma is a rare disease, affecting less than 1% of all hematological malignancies.**

**Core Concept:** Multiple myeloma is a plasma cell disorder characterized by the clonal proliferation of monoclonal plasma cells in bone marrow. These cells produce an abnormal immunoglobulin, leading to the accumulation of monoclonal protein (M-protein) in the blood and urine, which can cause various complications.

**Why the Correct Answer is Right:** Multiple myeloma is indeed a relatively rare disease among hematological malignancies. However, the question is incorrectly stating that it affects less than 1% of all hematological malignancies. The correct figure is approximately 1% of all hematological malignancies.

**Why Each Wrong Option is Incorrect:**

A. This option is incorrect because multiple myeloma is a well-established plasma cell disorder, as described in the core concept.
B. The statement is incorrect because multiple myeloma can indeed present with overlapping symptoms with other hematological malignancies, but this does not make the disease rare. It only highlights the importance of accurate diagnosis and differentiation from other disorders.
D. This option is wrong because multiple myeloma has seen significant improvements in treatment options and prognosis in recent years, despite the disease being rare. Improvements in diagnosis, management, and supportive care have led to better outcomes for patients with multiple myeloma.

**Clinical Pearl:**

While multiple myeloma is a rare disease, it is essential to be aware of the clinical manifestations and treatment advancements in this disorder to provide appropriate diagnosis and management for patients presenting with related symptoms.