ICD-10 Code C83.00 – Small cell B-cell lymphoma, unspecified site (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C83.00 – Small cell B-cell lymphoma, unspecified site
What it is
C83.00 identifies a small cell B-cell lymphoma when the site is not specified. Use it for a documented B-cell lymphoma composed of small malignant lymphocytes, but without a more precise anatomic location.
Clinical signs
Findings often include lymphadenopathy, splenomegaly, or other signs of indolent lymphoma. Clinical features vary; refer to documentation, pathology, and the provider’s lymphoma subtype description.
When to use this code
Use this code when the record clearly states small cell B-cell lymphoma and does not name a specific site. It also fits when the provider documents lymphoma involvement but the location is not further defined. If another subtype or site is documented, code that more specific diagnosis instead.
Do not use for
Do not use C83.00 for a different B-cell lymphoma subtype, such as diffuse or mantle cell lymphoma. Do not use it when the site is specified and a more exact code is available.
Coding tip
Code from the exact pathology or provider wording, and query if the lymphoma site or subtype is unclear.