Plasmacytosis

This code describes an abnormal increase in plasma cells within the bone marrow or other tissues. Plasmacytosis is a non-specific finding that can be reactive (e.g., due to infection or inflammation) or neoplastic (e.g., multiple myeloma, plasma cell leukemia).

Use this code when documentation explicitly states "plasmacytosis" without further specification of a definitive underlying plasma cell dyscrasia or other specific cause. This often occurs as an incidental finding on bone marrow biopsy or other tissue pathology reports.

• Do not use this code if a definitive diagnosis of multiple myeloma, solitary plasmacytoma, or other specific plasma cell neoplasm is documented; instead, code the specific neoplasm.
• Consider sequencing this code after a code for the underlying condition if the plasmacytosis is reactive and the cause is known (e.g., chronic inflammation).
• Always review the pathology report and physician's final diagnosis for the most specific and definitive diagnosis.