WBR0430
| Author | [[PageAuthor::Rim Halaby, M.D. [1], Alison Leibowitz [2] (Reviewed by Will Gibson)]] |
|---|---|
| Exam Type | ExamType::USMLE Step 1 |
| Main Category | MainCategory::Pathology |
| Sub Category | SubCategory::Hematology, SubCategory::Oncology |
| Prompt | [[Prompt::A 78-year-old male presents to the physician’s office with complaints of back pain, which is not relieved by medications, and fatigue of several weeks duration. Evaluation reveals anemia, elevated levels of serum calcium, and renal insufficiency. A peripheral smear of the patient’s blood shows characteristic “rouleaux formation”, characteristic of multiple myeloma. Which of the following markers is most frequently used for the staging of multiple myeloma?]] |
| Answer A | AnswerA::BUN/Creatinine ratio |
| Answer A Explanation | [[AnswerAExp::The BUN/Creatinine ratio aids in distinguishing between types of renal injury (pre-renal, instrinsic, or post-renal). It is not useful for staging multiple myeloma.]] |
| Answer B | AnswerB::β2 microglobulin and albumin levels |
| Answer B Explanation | AnswerBExp::Serum β2 microglobulin and albumin levels are used by the ISS for staging multiple myeloma. |
| Answer C | AnswerC::CA-125 level |
| Answer C Explanation | AnswerCExp::CA-125 levels are frequently checked in the follow-up of patients with ovarian cancer, but should not be used for diagnostic purposes. |
| Answer D | AnswerD::Serum calcium |
| Answer D Explanation | AnswerDExp::Multiple myeloma causes lytic lesions in the bone, thereby releasing stored calcium. However, serum calcium is not a prognostic marker for multiple myeloma patients. |
| Answer E | AnswerE::Spread to lymph nodes |
| Answer E Explanation | [[AnswerEExp::Most solid tumors utilize the TNM staging system in which the following three stages exist. Stage 1: Tumor is confined to the primary site. Stage 2: The tumor has spread to the lymph nodes. Stage 3: The tumor has distant metastases. In contrast, the International Staging System is used for multiple myeloma. Lymph node involvement is not one of the criteria in this framework.]] |
| Right Answer | RightAnswer::B |
| Explanation | [[Explanation::Multiple myeloma, a common hematologic cancer characterized by monoclonal gammopathy, frequently manifests with hypercalcemia, renal insufficiency, anemia, and lytic bone lesions (mnemonic: CRAB – Calcium, Renal, Anemia, Bone). Rouleaux formation on peripheral smear is also characteristic of multiple myeloma.
Multiple myeloma staging does not utilize the TNM system. Instead, the International Staging System (ISS) for multiple myeloma depends on levels of serum β2 microglobulin and albumin.
Stage I: Serum β2 microglobulin < 3.5 mg/L and serum albumin ≥ 3.5 g/dL Recall that β2 microglobulin is an important structural component of the functional MHC class I complex and is expressed by all nucleated cells. β2 microglobulin is overexpressed by myeloma cells for unknown reasons. β2 microglobulin is also readily filtered by the glomerulus and therefore reflects renal function. The serum concentration of β2 microglobulin thus reflects a combined measure of the tumor burden and decline in renal function in myeloma patients. It is the single greatest independent predictor of prognosis. |
| Approved | Approved::Yes |
| Keyword | WBRKeyword::Beta-2-microglobulin, WBRKeyword::Albumin, WBRKeyword::Multiple myeloma, WBRKeyword::Anemia, WBRKeyword::Hypercalcemia, WBRKeyword::Bone, WBRKeyword::Renal, WBRKeyword::Staging, WBRKeyword::ISS, WBRKeyword::Rouleaux formation, WBRKeyword::Rouleaux |
| Linked Question | Linked:: |
| Order in Linked Questions | LinkedOrder:: |