Follicular Lymphoma
Definition
- B lineage lymphoma demonstrating follicular architecture and composed of varying proportions of small cleaved cells and large cleaved and non-cleaved cells
Alternate/Historical Names
- Centroblastic lymphoma
- Centroblastic-centrocytic lymphoma
- Follicular center lymphoma, follicular
- Nodular histiocytic lymphoma
- Nodular lymphoma
- Nodular lymphoma, poorly differentiated (NLPD)
- Nodular mixed lymphoma
Diagnostic Criteria
- Uniform, densely packed follicles
- Frequently back to back
- May coalesce, simulating diffuse areas
- Median 47 follicles per 40x field (4x objective, 10x eyepiece)
- Compare to 30 per 40x field for reactive
- Frequently back to back
- Obliterates nodal architecture
- Compression of interfollicular stroma and vessels
- Highlighted by reticulin stain
- Extracapsular follicles may be seen
- Compression of interfollicular stroma and vessels
- Follicular population uniformly atypical
- Small cells have cleaved, twisted, indented, elongated, angulated nuclei
- Large cells may be cleaved or non-cleaved
- Interfollicular zone typically composed of small reactive cells
- Occasionally made up of neoplastic cells
- Epithelioid histiocytes may rarely be seen
- Ill defined mantle zones in most cases
- Usually indistinct borders
- Tingible body macrophages infrequent
- More frequent following steroid treatment
- No polarization of follicles
- Reactive follicles typically are polarized
- Small cells concentrated under mantle cap
- Large cells predominate at opposite pole
- Follicular lymphomas typically show no such polarization
- Occasionally seen in grade 2 follicular lymphoma
- Reactive follicles typically are polarized
- Mitotic figures less frequent in follicular lymphoma than reactive hyperplasia
- Grade 3 lymphoma may have high mitotic rate
- bcl2 and CD10 positive in 85% of cases
- bcl2 is quite specific vs. germinal centers
- CD10 is quite specific vs. other small B lymphomas
- Paratrabecular nodules indicate bone marrow involvement
- Circulating lymphoma cells have the appearance of buttock cells
- Diffuse areas may be identified
- Report as follicular and diffuse or follicular with diffuse areas
- 60-80% of cases eventually transform to large cell lymphoma, usually diffuse
- Distinguish from diffuse areas composed of same cell type as follicular areas
- Not related to therapy
- Occasional histologic features
- Plasma cells may be prominent in 10% of cases
- May be monotypic or polytypic
- Usually interfollicular
- If intra-follicular, the name follicular plasmacytoma has been used
- Serum paraprotein has been described
- Sclerosis
- May be broad or fine bands
- Not an independent prognostic factor
- Originally thought to be favorable
- Old term: nodular sclerotic lymphosarcoma
- Amorphous extracellular material
- PAS positive, diastase resistant
- EM shows membrane bound vesicles
- Similar finding sometimes seen in reactive follicles
- Rosettes of lymphoma cells surrounding eosinophilic material
- Center of rosette stains as cell membranes
- EM shows cytoplasmic processes
- Infarction
- Cerebriform and multilobated nuclei occasionally prominent
- Immunoblastic or plasmablastic features
- Cytologically similar to usual immunoblastic diffuse large B cell lymphoma
- Prominent nucleolus, abundant basophilic cytoplasm
- Rare, significance unknown
- Cytologically similar to usual immunoblastic diffuse large B cell lymphoma
- Following variants are not considered distinct clinico-pathologic entities and are described on separate pages, still within the overall heading of follicular lymphoma
- Plasma cells may be prominent in 10% of cases
Yasodha Natkunam MD PhD
Robert V Rouse MD
Department of Pathology
Stanford University School of Medicine
Stanford CA 94305-5342
Original posting:: May 1, 2006
