Is C91 a billable ICD-10-CM code?

No. C91 is a non-billable header code. Code to a higher level of specificity using one of its child codes.

Where does C91 sit in the tabular list?

Neoplasms (C00-D49), in the block Malignant neoplasms of lymphoid, hematopoietic and related tissue (C81-C96).

What cannot be coded together with C91?

C91 carries an Excludes1 note, which means the conditions it lists can never be coded together with it on the same encounter.

C91

C91 — Lymphoid leukemia

Non-billable headerICD-10-CM

C91 is a non-billable header ICD-10-CM code for lymphoid leukemia. It cannot be billed on its own: choose one of the more specific child codes below.

Excludes1 — never code together

These conditions cannot occur together. Billing both on the same encounter is a denial.

personal history of leukemia (Z85.6)

Other codes that can never be billed with C91

These codes carry an Excludes1 note pointing at C91. The conflict binds both ways, but ICD-10-CM only writes it down on one side — so you would not find this by reading C91 alone.

Z85.6Personal history of leukemia
C83.0Small cell B-cell lymphoma
C83.7Burkitt lymphoma
C84.ZOther mature T/NK-cell lymphomas
D72.825Bandemia
C94Other leukemias of specified cell type
D61.81Pancytopenia
D72.8Other specified disorders of white blood cells

Risk adjustment

C91 does not map to an HCC and does not risk-adjust under CMS-HCC V28. That is normal — most ICD-10 codes do not. It still needs to be coded correctly; it just will not move a RAF score.

Code to one of these instead C91

9 child codes. Green means billable.

Questions about C91

Is C91 a billable ICD-10-CM code?: No. C91 is a non-billable header code. Code to a higher level of specificity using one of its child codes.
Where does C91 sit in the tabular list?: Neoplasms (C00-D49), in the block Malignant neoplasms of lymphoid, hematopoietic and related tissue (C81-C96).
What cannot be coded together with C91?: C91 carries an Excludes1 note, which means the conditions it lists can never be coded together with it on the same encounter.