Search Database ICD-O-3 Code Lists

Name

Follicular lymphoma, grade 1

ICD-O-3 Morphology

9695/3: Follicular lymphoma, grade 1
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, grade 1 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)

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)

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.

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

Duodenal-type follicular lymphoma is particularly common in the second (descending) portion of the duodenum, sometimes with peripapillary clustering of lesions. In most cases, there are additional lesions throughout the small intestine and, less commonly, in the stomach, colon, and rectum

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

Duodenal-type follicular lymphoma (DTFL)
Malignant lymphoma, lymphocytic, poorly differentiated, nodular [OBS]
Malignant lymphoma, small cleaved cell, follicular [OBS]

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).

Duodenal-type follicular lymphoma (DTFL) is a variant of follicular lymphoma (FL) restricted to the gastrointestinal tract, mainly to the second portion of the duodenum. It is a neoplasm of germinal-center B cells showing a follicular architecture and is mostly limited to the mucosa. DTFLs are of low histological grade and have an indolent clinical course and excellent outcomes. (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/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)

C82.0 Non-Hodgkin lymphoma small cleaved cell, follicular

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

C82.0_ Follicular lymphoma grade I (effective October 01, 2015)
C82.0A Follicular lymphoma, grade I, in remission (effective October 01, 2024)

Signs and Symptoms

Drenching night sweats
Fatigue
Fever (for no known reason)
Lymphadenopathy (abdominal and thoracic)
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
Cytogenetics analysis
CT (CAT) scan
Flow cytometry
Immunohistochemistry
Immunophenotyping
Laparoscopy (rarely performed)
Laparotomy (rarely performed)
Lymph node biopsy
PET (positron emission tomography) scan

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: 437-439

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