IPLab:Lab 6:Multiple Myeloma

Clinical Summary

This 63-year-old female presented with the complaint of left chest pain of approximately 4 months duration. Physical examination revealed that the pain was along the distribution of the left sixth intercostal nerve. Chest film showed a posterior mediastinal mass with partial collapse of T6. A lytic lesion of the right distal clavicle was noted on subsequent radiological examination. A bone scan revealed increased uptake in thoracic vertebrae. Serum alkaline phosphatase was elevated slightly (143 U/L). Serum protein electrophoresis was normal, while urine protein electrophoresis showed a monoclonal spike in the Gamma region. A bone marrow study was non-diagnostic.

Autopsy Findings

A thoracotomy was performed after an unsuccessful needle biopsy. At thoracotomy, a 3-cm posterior mediastinal mass was identified that extended to within 1-2 mm of the aorta and into the interspace between the ribs.

Images

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  This is a low-power photomicrograph of the mediastinal mass. The mass is encapsulated and contains cellular areas (blue) and areas of pale red material.

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  This higher-power photomicrograph shows the junction between an amorphous hyaline-appearing area (amyloid) on the right and cellular areas (plasmacytoid cells) on the left.

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  This high-power photomicrograph demonstrates the cells that make up this tissue. These cells resemble plasma cells and are the malignant cell of multiple myeloma.

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  This is a photograph of the vertebral column from this patient at autopsy. Notice the collapsed vertebra (1). There are multiple variably-sized white nodules (2) within the bone marrow. These are accumulations of malignant plasma cells in this case of multiple myeloma.

Study Questions

• What class of amyloid is this?

AL - Immunocyte dyscrasias - primary amyloidosis.

• What is the chemical nature of this type of amyloid?

Immunoglobulin light chains, usually lambda.

• What is the usual organ distribution of amyloid in this class of amyloidosis?

Heart, gastrointestinal tract, peripheral nerves, skin, and tongue.