Chapter 2: Diagnosis Protocols

2.1 Overview of Diagnostic Criteria

The diagnosis of PCL typically involves a combination of clinical assessment, laboratory tests, and imaging studies. The key diagnostic features that distinguish PCL from other plasma cell disorders include:

Peripheral Blood Smear: Presence of >20% plasma cells in the blood.

Bone Marrow Biopsy: Confirmation of abnormal plasma cell proliferation.

Radiologic Imaging: To assess for bone lesions and other systemic impacts.

Laboratory Tests: Blood and urine tests to evaluate kidney function, calcium levels, and monoclonal proteins.

2.2 Blood Tests and Blood Count Interpretation

Blood Count:

Peripheral Blood Smear: This test will show the presence of circulating plasma cells, which is one of the primary features of PCL. Typically, >20% plasma cells in the peripheral blood is suggestive of PCL.

Complete Blood Count (CBC):

White Blood Cell Count (WBC): In PCL, WBC is often elevated due to the presence of plasma cells in circulation.

Normal Range: 4,000-11,000 cells per microliter

PCL: Can exceed 15,000-20,000 cells per microliter, depending on disease severity.

Hemoglobin (Hb): Often low, indicating anemia due to marrow infiltration by malignant cells.

Normal Range: 13-17 g/dL for men, 12-15 g/dL for women

PCL: May drop below 10 g/dL in advanced stages.

Serum Protein Electrophoresis (SPEP): This test helps detect monoclonal proteins (M-proteins), a hallmark of plasma cell disorders. In PCL, the M-protein is usually elevated.

Normal Range: Low or absent monoclonal proteins in the blood.

PCL: Presence of a monoclonal spike (M-spike) on electrophoresis, often associated with high levels of IgG or IgA, indicating an active plasma cell proliferation.

Understanding Blood Test Results:

WBC Count: A WBC count >20,000 cells per microliter is indicative of a potential PCL diagnosis.

Hemoglobin (Hb): Significant drops below the normal range, especially <10 g/dL, suggest anemia due to bone marrow infiltration.

Platelets: A platelet count under 50,000 can be a sign of marrow suppression due to plasma cell proliferation.

Creatinine and BUN: Elevated levels, especially if creatinine >1.5 mg/dL, can indicate kidney damage due to hypercalcemia or high M-protein levels.

Calcium: Normal Range: 8.5-10.5 mg/dL.

PCL: Hypercalcemia, with levels exceeding 12 mg/dL, may occur in advanced disease, leading to symptoms like nausea, vomiting, confusion, or constipation.

2.3 Bone Marrow Biopsy

A bone marrow biopsy is the gold standard for diagnosing PCL. This procedure involves the extraction of marrow from a bone (usually the hip) for examination under a microscope. The following are assessed:

Percentage of Plasma Cells: >20% plasma cells in the marrow confirms the diagnosis.

Plasmacytosis: An increased number of abnormal plasma cells in the marrow.

Cytogenetic Analysis: To look for chromosomal abnormalities like del(17p) or t(14;16) that are indicative of poor prognosis.

2.4 Imaging Studies

Imaging is essential for assessing the extent of the disease, particularly in detecting bone lesions that can be caused by PCL. Key imaging studies include:

X-rays: To identify bone lesions or fractures.

CT Scan: For more detailed images of bone and soft tissue involvement.

MRI: Often used to detect spinal cord compression or other soft tissue issues.

PET Scan: Can be used for staging and assessing the spread of disease.

2.5 Genetic and Molecular Testing

Cytogenetic Testing: Identifies genetic mutations or abnormalities that can predict disease progression.

FISH (Fluorescence In Situ Hybridization): A test used to detect chromosomal abnormalities such as del(17p) and t(14;16).

Gene Expression Profiling: Measures the activity of specific genes involved in the disease, helping to classify the disease and predict outcomes.

2.6 Diagnosis and Staging

The International Staging System (ISS) and Revised International Staging System (R-ISS) are commonly used for staging PCL. These systems assess:

Serum Beta-2 Microglobulin Levels: A marker of tumor burden.

Albumin Levels: Low levels indicate a poor prognosis.

Chromosomal Abnormalities: The presence of specific genetic mutations can indicate the severity and prognosis of the disease.

2.7 Diagnostic Protocols Summary

Clinical Assessment: History of symptoms, physical examination, and risk factors.

Blood Tests: CBC, serum electrophoresis, and calcium levels.

Bone Marrow Biopsy: Confirming plasma cell infiltration.

Imaging: To detect bone damage and other systemic effects.

Genetic Testing: To assess for high-risk genetic mutations and molecular markers.