ICD-10 Code C90.21 – Extramedullary plasmacytoma in remission (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C90.21 – Extramedullary plasmacytoma in remission
What it is
C90.21 identifies a history of extramedullary plasmacytoma that is currently in remission. Use it when the plasma cell tumor arose outside the bone marrow and is no longer active.
Clinical signs
Clinical features vary; refer to documentation. Typical records may note prior localized tumor, completed therapy, and no evidence of active disease on follow-up evaluation.
When to use this code
Use this code when the provider documents extramedullary plasmacytoma in remission, such as after treatment response or during surveillance visits. It fits follow-up encounters where the condition remains inactive but still affects ongoing care and history.
Do not substitute a generic plasma cell disorder code unless the record specifically states extramedullary plasmacytoma. Check documentation for whether the disease is active, in remission, or only part of past history.
Do not use for
Do not use C90.21 for active extramedullary plasmacytoma, multiple myeloma, or solitary bone plasmacytoma. If remission is not documented, check documentation before coding.
Coding tip
Assign C90.21 only when the provider clearly states “in remission” or an equivalent term in the assessment.