ICD-10 Code C90.3 – Solitary plasmacytoma (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C90.3 – Solitary plasmacytoma
What it is
Solitary plasmacytoma is a localized plasma cell tumor in a single bone or in soft tissue. It is coded when documentation shows one isolated lesion, not widespread multiple myeloma.
Clinical signs
Clinical features vary; refer to documentation. Common findings include a single destructive bone mass or an extramedullary plasma cell lesion confirmed by pathology, with no evidence of systemic disease.
When to use this code
Use C90.3 when the record clearly identifies a solitary plasmacytoma and supports that the disease is confined to one site. Apply it for biopsy-proven lesions described as plasmacytoma, whether bone-based or extramedullary, if no other myeloma sites are documented.
Check documentation for any mention of multiple lesions, marrow involvement, or progression to multiple myeloma, because those details may change code selection. You should code from the provider’s final diagnosis, not from a suspected mass alone.
Do not use for
Do not use this code for multiple myeloma, generalized plasma cell dyscrasia, or an unspecified bone tumor. If the chart does not confirm a solitary plasmacytoma, check documentation.
Coding tip
Verify that the record supports a single lesion and no systemic myeloma before assigning C90.3.