Lymphoma & related disorders
Mature B cell neoplasms
Follicular lymphoma
Pediatric type


Minor changes: 8 July 2020

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PubMed Search: Pediatric type follicular lymphoma

Mahsa Khanlari, M.D.
Jennifer Chapman, M.D.
Page views in 2019: 685
Page views in 2020 to date: 549
Cite this page: Khanlari M, Chapman JR. Pediatric type. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/lymphomafollicularchildhood.html. Accessed July 13th, 2020.
Definition / general
  • Localized neoplasm of germinal center B cells
  • Entirely follicular pattern
  • Lymph nodes of children and young adults
Essential features
  • At least partial effacement of nodal architecture
  • Pure follicular proliferation
    • Any component of diffuse large B cell lymphoma (DLBCL) excludes pediatric type follicular lymphoma (PTFL)
  • Nodal disease
  • Stage I - II
  • BCL6 positivity
  • BCL2 negativity or weak positivity
  • High proliferative fraction (> 30%)
  • No BCL2, BCL6, IRF4 or aberrant IG rearrangement
  • No BCL2 amplification
Terminology
  • Pediatric type nodal follicular lymphoma (PTNFL)
ICD coding
  • ICD-O: 9690/3 - follicular lymphoma, NOS
  • ICD-10: C82.90 - follicular lymphoma, unspecified, unspecified site
Epidemiology
  • 1 - 2% of all pediatric non-Hodgkin lymphoma
  • No upper age cutoff for diagnosis
  • Majority 5 - 25 years (< 40 years)
  • M:F = 10:1
  • Reference: Virchows Arch 2019;475:771
Sites
  • Head and neck lymph node, most frequent
  • Inguinal and axillary nodes, less frequent
Diagrams / tables

Pediatric type follicular lymphoma versus follicular lymphoma usual type
Pediatric type FL Usual type FL
Age Young Old age (sixth decade)
Stage Low (I - II) High (III - IV) in majority of cases
Location Head and neck Variable
Extranodal location Absent Present, variable
Histology Grade 3 Grade 1 - 3
BCL2 (IHC) Negative / dim Usually positive
CD10 Positive (~100%) Positive (usually)
Ki67 High Low (except for high grade)
t(14;18) IGH-BCL2 Absent Present, up to 90%
BCL6 or MYC rearrangements Absent Variably present
Genetic 1p36 loss Complex, variable
Mutations TNFRSF14, MAP2K1, IRF8 (K66R) CREBBP, EZH2, KMT2D
Prognosis Favorable Variable
FL: follicular lymphoma; IHC: immunohistochemistry
Clinical features
  • Young patients
  • Localized (stage I)
  • Commonly involves lymph nodes of the head and neck
  • Bone marrow involvement has not been reported
  • B symptoms are absent
  • Does not progress or recur after excision
  • References: Am J Surg Pathol 2013;37:333, Haematologica 2010;95:253
Radiology description
  • Localized nature of the disease
  • Absence of mediastinal or intraabdominal lymph node involvement
Prognostic factors
  • Excellent prognosis
  • 5 year survival of over 95%
Case reports
Treatment
Gross description
  • Lymph node: vaguely nodular pattern in cut section with bulging of node parenchyma
Frozen section description
  • Avoid specific diagnosis on frozen section due to requirement to examine submitted tissue completely to exclude a diffuse component and to confirm the absence of BCL2, BCL6 and MYC rearrangements
  • Cytogenetic analysis, flow cytometry, preparation of imprints should be considered
Microscopic (histologic) description
  • At least partial effacement of nodal architecture
  • Entirely follicular pattern
  • Expansile or serpiginous follicles
  • Absence of diffuse component
  • Rim of residual normal lymph node architecture at the periphery
    • So called node in node appearance
  • No extracapsular extension
  • Attenuated mantle zones
  • Monotonous population of intermediate sized blastoid cells within neoplastic follicles imparting a high grade or starry sky histologic appearance
  • Blastoid cells comprising the neoplastic follicles are morphologically distinct from both centrocytes and centroblasts
  • Tingible body macrophages present
  • Lack of polarization of germinal center
  • Reference: Haematologica 2010;95:253
Microscopic (histologic) images

Contributed by L. Jeffrey Medeiros, M.D. and Mahsa Khanlari, M.D.

Lymph node in 23 year old man

IHC for CD20

IHC for CD10


IHC for BCL6

IHC for BCL2

IHC for IgD highlighting mantle zone in lymph node

IHC for CD23 highlighting mantle zone in lymph node

Cytology description
  • 2 types of cytology:
    • Centroblastic cells
    • Monotonous, medium sized blastoid cells
      • Resemble centrocytes but are intermediate to large in size with more dispersed chromatin, high proliferative rate, frequent mitoses
      • Small nucleoli as compared with centroblasts
  • Reference: Am J Surg Pathol 2013;37:333
Positive stains
Negative stains
Molecular / cytogenetics description
Sample pathology report
  • Lymph node, left neck, excisional biopsy:
    • Pediatric type follicular lymphoma (see comment)
    • Comment: The patient is a 12 year old male presenting with isolated enlargement of left cervical lymph node. Other lymphadenopathy and extranodal masses as well as B symptoms are absent. Histologic sections show an excisional biopsy of lymph node demonstrating partial nodal architectural effacement. There is a rim of normal lymph node tissue in which reactive germinal centers are seen. Effaced areas of the lymph node are characterized by the presence of increased, irregularly shaped neoplastic follicles containing a monotonous population of intermediate sized lymphoid cells with blastic nuclear features. Mitotic activity is brisk and tingible body macrophages are present. A diffuse component is not identified. The lymph node is submitted entirely for histologic evaluation. By immunohistochemistry, the neoplastic cells are positive for CD20, CD10, BCL6 and HGAL and negative for CD3 and CD5. A subset of neoplastic cells express dim BCL2, but the majority are negative. The proliferative rate of lymphoid cells within neoplastic follicles is ~60%. FISH studies have been performed and are negative for the presence of BCL2, BCL6, MYC and IRF4 rearrangements. Next generation sequencing has been performed and has identified the presence of a TNFRSF14 mutation. The above histologic, immunophenotypic and cytogenetic features, in the appropriate clinical context, support the diagnosis of pediatric type follicular lymphoma.
Differential diagnosis
Board review style question #1
Which of the following genetic mutations appears to be relatively specific for pediatric type follicular lymphoma?

  1. CREBBP
  2. IRF8 (K66R, p.L66A)
  3. KMT2D
  4. MAP2K1
Board review answer #1
B. IRF8 (K66R, p.L66A). It has been identified in a subset of cases (3 of 6 in this series) (Mod Pathol 2016;29:1212). Larger studies are probably needed to determine the level of specificity.

Comment Here

Reference: Pediatric type follicular lymphoma (PTFL)
Board review style question #2

A 23 year old man presented with a right cervical lymph node enlargement. Cut section of the lymph node is provided in images. Which of the following is true?

  1. Chance of recurrence after resection is high
  2. Diagnosis does not require cytogenetic testing
  3. Diagnosis requires integration of morphology with lymphoma staging findings
  4. Frequent CREBBP mutation
Board review answer #2
C. Diagnosis requires integration of morphology with lymphoma staging findings (Am J Surg Pathol 2013;37:333).

Comment Here

Reference: Pediatric type follicular lymphoma (PTFL)
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