This category includes:

• Nodal TFH cell lymphoma, angioimmunoblastic-type
• Nodal TFH cell lymphoma, follicular-type
• Nodal TFH cell lymphoma, NOS

Nodal TFH cell lymphoma, angioimmunoblastic-type

Introduction:

• Neoplasm of mature T-cells with a TFH phenotype, characterised by systemic disease and a polymorphous lymphoid infiltrate involving lymph nodes, accompanied by a prominent proliferation of high endothelial venules and follicular dendritic cells

Epidemiology:

• Account for 1-2% of all NHL
• 13-24% of peripheral T cell lymphomas
• Incidence 1/10lac/year
• Median age- 60 years
• M:F= 1:1

Etiology:

• Immunodeficiency
• EBV
• Angioimmunoblastic lymphadenopathy

Pathogenesis:

• VEGF transcripts are detected
• DNMT3A mutations
• TET2 mutations

Clinical Features:

• Generalized peripheral lymphadenopathy
• Hepatosplenomegaly
• Skin rash with pruritus
• B Symptoms
• Polyclonal hypergammaglobulinemia
• Rarely- Edema, Pleural effusion, Arthritis, Ascites
• Autoimmune phenomenon- AIHA, Vasculitis, Rheumatoid arthritis, Autoimmune thyroid disease
• Recurrent infections

Investigations:

• Lymph node
  • Effaced architecture
  • Regressed follicles
  • Paracortex is diffusely infiltrated by polymorphous population of small to medium sized lymphocytes (show minimal cytological atypia)
  • Abnormal lymphoid cells are admixed with small, reactive lymphocytes,eosinophils, plasma cells, histiocytes.
  • Increased number of follicular dendritic cells
  • High endothelial venules are abundant and show arborization
• Immunophenotyping
  • Mature T cells – usually admixture of CD4 & CD8 cells
  • Tumor cells are positive for 
    • Pan T markers- CD3, CD4, CD2 and CD5
    • TFH markers- PD1 (CD279), ICOS, BCL6, CXCL13 and CD10
  • Negative: CD8
  • Plasma cells – Polyclonal
  • Follicular dendritic cells – CD21+, CD23+, CD35+ (Surround the high endothelial venules)
• Molecular studies- Rearrangement of TCR
• Cytogenetics- Trisomy 3, Trisomy 5, Additional X-chromosome
• Hemogram- Anemia, eosinophilia, sometimes pancytopenia
• S. Protein electrophoresis- Polyclonal hypergammaglobulinemia
• LDH- Increased
• ESR- Increased
• DCT- Positive
• BMA- Involvement is seen in 60% patients
• RA factor and anti-smooth muscle antibody- May be positive

Prognosis:

• Overall prognosis is poor
• Median survival - < 3 years
• Rarely AITL spontaneously regresses
• Alternative prognostic index for AITL- Following factors are included
  • Age- >60 years
  • Performance score- >1
  • Extranodal site- >1
  • B symptoms
  • Platelet count <1.5lac/cmm

Treatment:

• Follow guidelines of PTCL-NOS
• CR rates are 50%, but relapse rate is high
• Routine CNS prophylaxis is not warranted
• Interferon alpha or cyclosporine can be used as maintenance

Nodal TFH cell lymphoma, follicular-type

• It is a peripheral T-cell lymphoma with a TFH phenotype, which displays a follicular growth pattern and lacks the high endothelial venule and extrafollicular follicular dendritic cell proliferation

Nodal TFH cell lymphoma, NOS

• It is a peripheral T-cell neoplasm with a TFH phenotype, demonstrated by the expression of CD4 and at least two TFH markers, which does not fulfil the required histopathological criteria for nTFHL, angioimmunoblastic-type or nTFHL, follicular-type.