USMLE (United States Medical Licensing Examination) Step 1 Practice Exam

Which condition is associated with primary amyloidosis (AL) and punched-out lytic bone lesions on x-ray?

1. Chronic Kidney Disease

2. Polycythemia Vera

3. Carbon Monoxide Poisoning

4. Multiple Myeloma

The correct answer is: Multiple Myeloma

Primary amyloidosis, also known as AL amyloidosis, occurs due to the deposition of immunoglobulin light chains in various tissues, often associated with plasma cell dyscrasias. One of the conditions linked with AL amyloidosis is multiple myeloma, which is a malignancy of plasma cells characterized by the overproduction of monoclonal immunoglobulin. In the context of multiple myeloma, patients often present with "punched-out" lytic bone lesions on X-ray due to the osteoclastic activity stimulated by the excess osteoclast-activating factors secreted by the neoplastic plasma cells. These lytic lesions result from localized bone destruction and are a hallmark feature of multiple myeloma. Patients with multiple myeloma may also develop AL amyloidosis as a complication due to the high levels of light chains produced. Thus, the association of primary amyloidosis with multiple myeloma is clinically significant, as the underlying plasma cell disorder not only leads to the disease process itself but also contributes to the characteristic skeletal findings, including the distinct "punched-out" lesions observed on imaging studies. In summary, the relationship between primary amyloidosis and multiple myeloma is crucial, as