ICD-10 Code C91.62 – Prolymphocytic leukemia of T-cell type, in relapse (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C91.62 – Prolymphocytic leukemia of T-cell type, in relapse
What it is
C91.62 identifies a relapse of prolymphocytic leukemia of T-cell type. Use it when the record states this T-cell leukemia has returned after prior remission or response.
Clinical signs
Clinical features vary; refer to documentation. Typical notes may describe recurrent leukemia with abnormal T-lymphocytic proliferation, often confirmed by hematology evaluation and pathology.
When to use this code
Use C91.62 when the provider documents relapsed T-cell prolymphocytic leukemia, recurrent disease, or return of the same leukemia after prior treatment. The record should clearly indicate relapse rather than initial diagnosis or remission status. Check documentation if the type or disease phase is unclear.
Do not use for
Do not use this code for newly diagnosed T-cell prolymphocytic leukemia without relapse, or for other leukemia subtypes. If the chart only says “history of leukemia” or “in remission,” choose the documented status instead.
Coding tip
Confirm both the T-cell type and relapse wording in the provider note before assigning C91.62.