[Plasma cell leukemia presenting with cleaved nuclei and a monocytoid appearance]

Area of Science:

• Hematology
• Oncology
• Immunology

Background:

• Plasma cell leukemia (PCL) is a rare and aggressive malignancy characterized by the proliferation of plasma cells in the peripheral blood.
• Diagnosis typically relies on morphological examination, immunophenotyping, and detection of monoclonal proteins.

Observation:

• A 74-year-old male presented with anemia, thrombocytopenia, and leukocytosis with abnormal cells exhibiting cleaved and monocytoid nuclei.
• Bone marrow examination revealed infiltration by abnormal cells (43.6%) negative for peroxidase and positive for PAS staining.
• Initial surface antigen analysis showed no expression of common lymphoid and myeloid markers (CD2, 3, 4, 8, 10, 19, 20, 13, 33).

Findings:

• Serum immunoelectrophoresis identified a kappa-type IgA monoclonal band.
• Immunostaining confirmed IgA and kappa-type expression on the abnormal cells.
• Later surface antigen analysis revealed CD38 expression, aiding in the diagnosis of plasma cell leukemia despite unusual morphology.

Implications:

• This case underscores the importance of comprehensive immunophenotyping, including specific markers like CD38, in diagnosing plasma cell leukemia.
• Immunostaining is essential for differentiating PCL, especially when morphological features are atypical or present in the context of leukocytosis.
• Accurate diagnosis through advanced techniques is critical for appropriate treatment strategies and improved patient outcomes in plasma cell leukemia.