ICD-O-1 Morphology

Effective 1978 - 1991

ICD-O-2 Morphology

Effective 1992 - 2000

ICD-O-3 Morphology

Effective 2001 and later


for cases diagnosed 1978 and later

Primary Site(s)

See Module 3: Rules PH5, PH6
Most common sites of involvement: bone marrow, peripheral blood, lymph nodes


Not Applicable

Module Rule

Module 3: PH5, PH6


Chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) is a neoplasm composed of monomorphic small mature B cells that coexpress CD5 and CD23. There must be a monoclonal B-cell count greater than or equal to 5 x 10 (to the ninth (9th))/L, with the characteristic morphology and phenotype of CLL, in the peripheral blood.

The 2016 revision of the WHO classification of lymphoid neoplasms has added monoclonal B-cell lymphocytosis (MBL) as an alternate name for CLL. Variants of MBL include "low count" (PB CLL) and "high count." MBL precedes almost all cases of CLL/SLL. Low count MBL has significant differences from CLL, with limited chance of transformation and does not require follow up care outside of routine care. In contrast, high count MBL requires routine follow-up and is very similar to Rai stage 0 CLL.

Abstractor Notes

Code 9823/3 is used for CLL, SLL, and CLL/SLL. CLL and SLL are no longer coded separately because it is almost impossible to differentiate between the two diseases. See the hematopoietic PH rules for information on coding primary site for CLL/SLL. CLL is the most common leukemia of adults in Western countries.

CLL is frequently diagnosed by flow cytometry (immunophenotyping), but can also be diagnosed via biopsy (bone marrow).

Flow cytometry is also used for ZAP 70, which is a predictor for aggressive vs indolent disease. If the ZAP 70 is positive, that means the disease is more aggressive and will need closer follow up. If the ZAP 70 is negative, then the disease is on a more indolent course. If the disease is more aggressive, treatment timing will change.

Treatments include donor lymphocyte infusion, which is a type of immunotherapy.

The treatment-free survival time was 30 months for ZAP-70 negative patients and 18 months for ZAP-70 positive patients.

Definitive Diagnostic Methods

Flow cytometry
Genetic testing
Histologic confirmation

Genetics Data

BCR stereotype
IG gene rearrangement
Ig heavy and light chain genes rearranged; abnormal karyotypes in 80%:trisomy 2: 20%, del at 13q14 in 50%, del at 11q22-23 in 20%, del at 6q21 in 5%, del at 17p13 in 10%
IGHV (highly sweked and mutated)


CD19 expressed
CD20 expressed
CD22 expressed
CD79b expressed
Cyclin D1 not expressed
FMC7 negative or weakly expressed
LEF1 aberrantly expressed
Weak or dim surface IgM/IgD


Hormone therapy

Transformations from


Corresponding ICD-9 Codes

200.8 Other named variants, lymphoma (SLL) (Lymphoma presentation)
204.1 Chronic lymphoid leukemia

Corresponding ICD-10 Codes

C83.0 Small B-cell lymphoma (SLL) (Lymphoma presentation)
C91.1 Chronic lymphocytic leukemia (CLL) (Leukemia presentation)

Corresponding ICD-10-CM Codes (U.S. only)

C83.0 Small cell B-cell lymphoma (SLL) (Lymphoma presentation) (effective October 01, 2015)
C91.1 Chronic lymphocytic leukemia of B-cell type (CLL) (Leukemia presentation) (effective October 01, 2015)

Diagnostic Exams

CT (CAT) scan
Complete blood count (CBC)
Laparoscopy (rarely performed)
Laparotomy (rarely performed)
MRI (magnetic resonance imaging)
PET (positron emission tomography) scan

Progression and Transformation

2-8% of CLL patients transform to DLBCL
<1% of CLL patients develop classical Hodgkin lymphoma

Epidemiology and Mortality

Age: 65 years median age (diagnosis in younger adults increasing)
Incidence: 2-6 cases per 100,000 per person per year (most common leukemia in adults in Western countries)
Race: slight female predominance


Swerdlow SH, Campo E, Harris NL, Jaffe ES, Pileri SA, Stein H, Thiele J (Eds):
WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues (Revised 4th edition)
IARC: Lyon 2017
Section: Mature B-cell neoplasms
Pages: 216-220

International Classification of Diseases for Oncology, Third Edition, First Revision. Geneva: World Health Organization, 2013.
Section: ICD-O-3.1 (2011) Morphological Codes
Pages: http://codes.iarc.fr/codegroup/2

National Cancer Institute
Section: General Information About Adult Non-Hodgkin Lymphoma (NHL)
Pages: https://www.cancer.gov/types/lymphoma/hp/adult-nhl-treatment-pdq