ICD-10 Code C91.3 – Prolymphocytic leukemia of B-cell type (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C91.3 – Prolymphocytic leukemia of B-cell type
What it is
C91.3 identifies B-cell prolymphocytic leukemia, a rare and aggressive leukemia of mature B lymphocytes. Use it when the record specifically documents this diagnosis.
Clinical signs
Clinical features vary; refer to documentation. Common findings may include marked lymphocytosis, splenomegaly, and circulating prolymphocytes on peripheral blood review.
When to use this code
Use C91.3 when the provider documents B-cell prolymphocytic leukemia, including confirmed new diagnoses and established disease in follow-up notes. It is appropriate when pathology, hematology, or oncology documentation names this subtype. If the subtype is unclear, check documentation before coding.
Do not use for
Do not use this code for unspecified leukemia, chronic lymphocytic leukemia, or T-cell prolymphocytic leukemia. If the record does not clearly state B-cell type, check documentation.
Coding tip
Code only when the chart explicitly identifies B-cell prolymphocytic leukemia; otherwise query for the exact leukemia subtype.