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

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.

Diagnostic Confirmation

This histology can be determined by positive histology (including peripheral blood) with or without genetics and/or immunophenotyping. Review the Definitive Diagnostic Methods, Immunophenotyping and Genetics Data sections below, and the instructions in the Hematopoietic Manual for further guidance on assigning Diagnostic confirmation.


Not Applicable

Module Rule

Module 3: PH5, PH6

Alternate Names

All variants of BCLL
Chronic lymphatic leukemia
Malignant lymphoma, lymphocytic, diffuse, NOS
Malignant lymphoma, lymphocytic, NOS
Malignant lymphoma, lymphocytic, well differentiated, diffuse
Malignant lymphoma, small B lymphocytes, NOS
Malignant lymphoma, small cell diffuse
Malignant lymphoma, small cell, NOS
Malignant lymphoma, small lymphocytic, diffuse
Malignant lymphoma, small lymphocytic, NOS


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.

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)
tyrosine kinase ZAP-70


CD5+ (expression/positive)
CD10- - (no expression/negative)
CD19+ (expression/positive)
CD20+ (expression/positive)
CD22+ (expression/positive)
CD23+ (expression/positive)
CD43+ (expression/positive)
CD79b+ (expression/positive)
CD200+ (expression/positive)
Cyclin D1- (no expression/negative)
FMC7 - (no expression/negative) or weak expression/positive
LEF1+ (aberrant expression/positive) aberrantly expressed
Weak or dim surface IgM/IgD


Hormone therapy

Transformations from


Corresponding ICD-9 Codes

204.1 Chronic lymphoid leukemia (CLL)

Corresponding ICD-10 Codes

C91.1 Chronic lymphocytic leukemia (CLL)

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

C91.1 Chronic lymphocytic leukemia of B-cell type (CLL) (effective October 01, 2015)

Signs and Symptoms

Autoimmune hemolytic anemia
Extranodal infiltrates

Diagnostic Exams

Blood chemistry studies
CT (CAT) scan
Cytogenetic analysis
Flow cytometry
Laparoscopy (rarely performed)
Laparotomy (rarely performed)
Lymph node biopsy
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
Survival: 293 month median survival


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, Second Revision. Geneva: World Health Organization, 2020.
Section: ICD-O-3.2 (2020) Morphological Codes
Pages: http://www.iacr.com.fr/index.php?option=com_content&view=category&layout=blog&id=100&Itemid=577

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