In situ follicular neoplasia

Follicular lymphoma in situ

In situ follicular lymphoma

Intrafollicular neoplasia

ISFN

In situ follicular neoplasia (ISFN), formerly referred to as follicular lymphoma in situ, is defined as partial or total colonization of germinal centers by clonal B cells carrying the BCL2 translocation characteristic of FL in an otherwise reactive lymph node. It can also been seen in reactive follicles in lymphoid tissue in other sites, including the spleen. ISFN is biologically similar to the presence of cells carrying the BCL2 rearrangement found in the peripheral blood of otherwise healthy individuals by PCR amplification for BCL2 rearrangement.

ISFN should be distinguished from lymph nodes showing only partial involvement by FL. Although patients with partial involvement tend to have lower-stage disease, partial involvement is considered a form of FL (9690/3, 9691/3, 9695/3, 9698/3) for clinical purposes.

238.79 Other lymphatic and hematopoietic tissues

D47.7 Other specified neoplasms of uncertain or unknown behavior of lymphoid, hematopoietic, and related tissue

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: 274-275

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