Search Database ICD-O-3 Code Lists

Name

Follicular lymphoma (FL), NOS

ICD-O-3 Morphology

9690/3: Follicular lymphoma, NOS
Effective 2001 and later

Reportable

for cases diagnosed 1978 and later

Primary Site(s)

See Module 7
Most common sites of involvement: lymph nodes, Waldeyer ring, skin, duodenum, ocular adnexa, breast and testis.
Common metastatic sites include the bone marrow/peripheral blood.
Spleen involvement is common due to dissemination of disease

See abstractor notes

Coding Manual: Hematopoietic Coding Manual (PDF)

Abstractor Notes

Follicular lymphoma, NOS (FL) is part of the Mature B-cell neoplasms lineage table in the WHO 5th edition of Hematolymphoid Tumors. (See Appendix B in the Hematopoietic Manual, Table B15)

Follicular lymphoma, NOS is a generic disease description. DCO cases or path report only cases usually stay in this classification. The NOS histology may be the working diagnosis. Further review of the medical record should be done to look for the tests listed as definitive diagnosis.

There are several follicular lymphoma subtypes
1. Follicular lymphoma, NOS (9690/3)
2. Follicular lymphoma, grade 1 (9695/3)
3. Follicular lymphoma, grade 2 (9691/3)
4. Follicular lymphoma, grade 3, 3A, 3B (9698/3)
5. Duodenal-type follicular lymphoma (9695/3)
6. Large B-cell lymphoma with IRF4 rearrangement (9698/3)
7. Pediatric-type follicular lymphoma. (9695/3)

Follicular lymphomas are always the same primary. When there are multiple diagnoses of Follicular lymphoma, update the histology (as needed) to always reflect the highest grade. Known grade always takes priority over the NOS histology. (See Rule M2 in the Hematopoietic manual).

Priority order:
1. 9698/3: Follicular lymphoma, Grade 3, 3A, 3B
2. 9691/3: Follicular lymphoma, Grade 2
3. 9695/3: Follicular lymphoma, Grade 1
4. 9690/3: Follicular lymphoma, NOS

Most patients have widespread disease at diagnosis, including peripheral and central (abdominal and thoracic) lymphadenopathy and splenomegaly. Most patients present with peripheral lymphadenopathy, but any nodal group can be involved. A pure extranodal presentation is uncommon but can occur in almost any extranodal site.

For Pediatric-type follicular lymphoma, almost all cases manifest as limited-stage peripheral lymphadenopathy. Most patients present with a single enlarged lymph node in the head and neck region. Extranodal presentation is excluded from this definition.

When any area of diffuse large-B-cell lymphoma (DLBCL) is present in a FL the disease should be reported as diffuse large B-cell lymphoma (9680/3) (See M4, PH15).

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.

Module Rule

None

Alternate Names

BCL2-R-negative CD23-positive follicle centre lymphoma
Classic Follicular Lymphoma (cFL)
Follicular lymphoma, low grade
Follicular lymphoma with a predominantly diffuse growth pattern (dFL)
Follicular lymphoma with uncommon features
Follicular lymphoma with unusual cytological features (uFL)
Malignant lymphoma, centroblastic-centrocytic, follicular [OBS] (see 9675/3 prior to 2010)
Malignant lymphoma, centroblastic-centrocytic, NOS [OBS] (see 9675/3 prior to 2010)
Malignant lymphoma, follicle center, follicular [OBS]
Malignant lymphoma, follicle center, NOS [OBS]
Malignant lymphoma, follicular, NOS
Malignant lymphoma, lymphocytic, nodular, NOS [OBS]
Malignant lymphoma, mixed cell type, diffuse [OBS[ (see 9675/3 prior to 2010)
Malignant lymphoma, mixed small and large cell, diffuse (see 9675/3 prior to 2010)
Malignant lymphoma, nodular, NOS [OBS]
Pediatric-type follicular lymphoma (PTFL)

Definition

Follicular lymphoma (FL) is a neoplasm of germinal-center (GC) B cells with varying proportions of centrocytes and centroblasts or large transformed cells and at least a partially follicular growth pattern. In rare cases with an entirely diffuse growth pattern, the neoplastic cells should still show GC B-cell morphology and immunophenotype. (WHO 5th edition)

Pediatric-type follicular lymphoma (PTFL) is a localized, nodal mature B-cell lymphoma occurring predominantly in the pediatric, adolescent, and young adult age group. It is characterized by a clonal proliferation of germinal-center B cells with a pure follicular growth pattern, altered lymph nodal architecture, a high proliferation index, and an absence of BCL2, BCL6, and IRF4 rearrangements. Marginal zone differentiation may be present. (WHO 5th edition)

Definitive Diagnostic Methods

Cytogenetics
Genetic testing
Histologic confirmation
Immunohistochemistry
Immunophenotyping

Genetics Data

BCL2 rearrangement
BCL6 rearrangement
IG heavy chain and light chain genes monoclonally rearranged

Immunophenotyping

BCL6+ (expression/positive)
CD10 expression and positive
GCET1+ (expression/positive)
GCET2 (HGAL)+ (expression/positive)
LMO2+ (expression/positive)
MEF2B+ (expression/positive)

Treatments

Chemotherapy
Hematologic Transplant and/or Endocrine Procedures
Immunotherapy
Radiation therapy

Transformations to

Transformations from

None

Same Primaries

Corresponding ICD-10 Codes (Cause of Death codes only)

C82.9 Follicular non-Hodgkin lymphoma, unspecified

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

C82.8_ Other types of follicular lymphoma (effective October 01, 2015)
C82.8A Other types of follicular lymphoma, in remission (effective October 01, 2024)
C82.9_ Follicular lymphoma, unspecified (effective October 01, 2015)
C82.9A Follicular lymphoma, unspecified, in remission (effective October 01, 2024)

Signs and Symptoms

Drenching night sweats
Fatigue
Fever (for no known reason)
Lymphadenopathy (abdominal and thoracic)
Pain in chest, abdomen or bones (for no known reason)
Painless swelling in the lymph nodes in the neck, underarm, groin or stomach
Skin rash or itchy skin
Splenomegaly
Weight loss for no known reason

Diagnostic Exams

Blood chemistry studies
Bone marrow aspiration and biopsy
CT (CAT) scan
Cytogenetic analysis
Flow cytometry
Immunohistochemistry
Immunophenotyping
Laparoscopy (rarely performed)
Laparotomy (rarely performed)
Lymph node biopsy

Progression and Transformation

25-35% of patients transform to DLBCL

Epidemiology and Mortality

Age: 60 years median age (rare occurrence under 20 years of age)
Incidence: Follicular lymphomas account for 20% of all lymhpomas
Sex: slight female predominance
Survival: 8-15 years median survival, closely related to the extent of the disease at diagnosis

Sources

WHO Classification of Tumours Editorial Board. Haematolymphoid tumours. Lyon (France): International Agency for Research on Cancer; 2024. (WHO classification of tumours series, 5th ed.; vol. 11). https://publications.iarc.who.int/637.
Section: Follicular Lymphoma
Pages: Part B: 423-433

International Classification of Diseases for Oncology, 3rd edition (including revisions). Geneva: World Health Organization, 2001, 2011, 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

PDQ® Adult Treatment Editorial Board. PDQ Indolent B-Cell Non-Hodgkin Lymphoma Treatment. Bethesda, MD: National Cancer Institute. Updated <02/18/2025>. Available at: https://www.cancer.gov/types/lymphoma/hp/indolent-b-cell-lymphoma-treatment-pdq. Accessed <03/04/2025>. [PMID: 37437080]
Section: Indolent B-Cell Non-Hodgkin Lymphoma Treatment (PDQ®)–Health Professional Version
Pages: https://www.cancer.gov/types/lymphoma/hp/adult-nhl-treatment-pdq
Glossary