A 76-year-old gentleman presents to the ED with complaints of bone pain and fatigue.
- What diagnosis unifies the below CBC findings?
- What additional investigations would you send to support the diagnosis?
Click for answer:
Diagnosis: plasma cell leukemia
CBC Clues:
(1) Cytopenias
(2) Leucoerythroblastic anemia
(3) Circulating plasma cells
Q1: What diagnosis unifies the below CBC findings?
Plasma cell leukemia
Q2: What additional investigations would you send to support the diagnosis?
SPEP and serum FLC
CRAB Symptoms
• Calcium (hyper)
• Renal impairment
• Anemia (often normocytic)
• Bony involvement
This patient is presenting with evidence of peripheral plasma cells and symptoms suggestive of multiple myeloma (bony pain). Plasma cells are terminally differentiated B cells that are normally found in the bone marrow and the spleen. They should not be seen in peripheral blood.
Plasma cell leukemia is a rare form of multiple myeloma where plasma cells circulate in the peripheral blood. Other plasma cell disorders include multiple myeloma (MM), solitary plasmacytoma, and monoclonal gammopathy of unknown significance (MGUS).
CBC Pearls
• Plasma cells on CBC suggest plasma cell disorder
• SPEP + sFLC is the screening test of choice for MM
Typical signs and symptoms of MM are remembered by the CRAB acronym (see Box). Initial testing for MM should include serum protein electrophoresis (SPEP) and either serum free light chains (sFLC) or 24-hour urinary protein electrophoresis (UPEP). sFLC is often preferred in combination with SPEP as it is less cumbersome than a 24-hour urine collection and has high sensitivity. Additional work-up should include quantitative immunoglobulins, creatinine, electrolytes (including calcium), and skeletal survey/low-dose CT. A bone marrow biopsy is required for diagnosis.