A Review of Hematologic Malignancies for the Physician Assistant Exam
For the Physician Assistant Exam (PANCE), you will need to know various hematologic malignancies. They include multiple myeloma, amyloidosis, leukemia, and lymphoma. They can occur together, or they can occur separately. They can also affect multiple organs of the body, a big one being the kidney. Co-author Rich sees a lot of these conditions in his clinical practice.
Multiple myeloma (MM) is referred to as a plasma cell dyscrasia. It’s cancer of the plasma cell (the memory cell), and it most frequently affects older adults. This condition can be deadly. Here are the key points concerning multiple myeloma:
Clinical presentation includes back pain and weight loss. Initial presentation can be a fracture after a fall that reveals a cancer (pathologic fracture).
Initial lab abnormalities suggestive of multiple myeloma include anemia, kidney failure, hypercalcemia, an increased total protein level, and an elevated sedimentation rate.
Screening tests for multiple myeloma include a serum and protein electrophoresis (SPEP and UPEP) to look for this paraprotein. You’re looking for a monoclonal spike (or M spike) on the SPEP. Other parts of the initial examination are a serum-free light chain assay and serum immunoelectrophoresis. Bence Jones proteins (light chains of immunoglobulin) are found in the urine.
The diagnosis of multiple myeloma is made by the degree of the M spike seen on the SPEP. As people get older, they can become carriers of this paraprotein without having features of multiple myeloma. This condition is called monoclonal gammopathy of undetermined significance (MGUS).
You make the confirmatory diagnosis by bone marrow biopsy, looking for more than 10 percent plasma cells in the bone marrow.
Other testing includes a skeletal survey, looking for lytic lesions.
The treatment is chemotherapy, which can include melphalan and steroids like prednisone or dexamethasone. Thalidomide has been used, as well as newer agents like bortezomib, which is a monoclonal antibody.
If you see a question asking for a radiologic study to search for multiple myeloma, the answer is not bone scan or MRI. The skeletal survey using radiographs is preferred for this diagnosis. Remember that multiple myeloma is only osteolytic, not osteoblastic. If you’re asked about staging for a solid organ cancer with osteoblastic activity (such as prostate or breast cancer), then the answer would be bone scan.
A condition closely related to multiple myeloma is amyloidosis. It’s an abnormal, toxic, inflammatory protein that can deposit in places that it shouldn’t and cause some major damage. Approximately 10 percent of people diagnosed with multiple myeloma can have coexistent amyloidosis, although amyloidosis can exist on its own. We’re referring here to primary amyloidosis — there can be several different types of amyloidosis. Here are some key facts concerning primary amyloidosis:
Amyloidosis can affect multiple organs in the body, including the nerves (peripheral neuropathy), the heart (cardiac amyloidosis), and the kidneys (renal failure and proteinuria).
You can make the diagnosis by doing an abdominal-wall fat pad biopsy. If needed, you can biopsy a specific organ (for example, the kidney if kidney disease is present). A positive Congo red stain under polarized light is diagnostic for amyloidosis.
The treatment for amyloidosis is chemotherapy.
Know that when amyloidosis affects the kidney, proteinuria and kidney failure occur. Multiple myeloma can also affect the kidney in a number of ways, including myeloma cast nephropathy and light chain disease, which can also cause proteinuria. Both multiple myeloma and amyloidosis can cause the kidneys to appear enlarged on kidney ultrasound.