Approach to nodal-based T-cell lymphomas: Pathology Case Report

Summary

Peripheral T-cell lymphomas (PTCLs) represent a heterogeneous group of uncommon malignancies derived from mature T cells and usually characterised by an aggressive clinical course. Their clinical presentation, localisation and pattern of dissemination are highly variable, but the majority of cases present as nodal diseases. The recently revised classification of lymphomas has incorporated many new molecular genetic data derived from gene expression profiling and next generation sequencing studies, which refine the definition and diagnostic criteria of several entities. Nevertheless, the distinction of PTCL from various reactive conditions, and the diagnosis of PTCL subtypes remains notably challenging. Here, an updated summary of the clinicopathological and molecular features of the most common nodal-based PTCLs (angioimmunoblastic T-cell lymphoma and other nodal lymphomas derived from follicular T helper cells, anaplastic large cell lymphomas and peripheral T-cell lymphoma, not otherwise specified) is presented. Practical recommendations in the diagnostic approach to nodal T-cell lymphoproliferations are presented, including indications for the appropriate use and interpretation of ancillary studies. Finally, we discuss commonly encountered diagnostic problems, including pitfalls and mimics in the differential diagnosis with various reactive conditions, and the criteria that allow proper identification of distinct PTCL entities.

Pathological features of nodal-based PTCLS

Angioimmunoblastic T-cell lymphoma (AITL)

AITL is the most common specific type of PTCL and is more common in North America and Europe than in Asia.9 AITL is derived from TFH cells10 and manifests as a systemic disease in adults, usually elderly individuals. Patients present with generalised peripheral lymphadenopathy, often with extranodal involvement and systemic symptoms (fever, weight loss, skin rash, arthralgias, etc.). Immune abnormalities like polyclonal hypergammaglobulinaemia and Coombs-positive haemolytic anaemia are frequent and typical of AITL, but not mandatory for the diagnosis. The median survival is <3 years, but a subset of patients experience long-term survival.

Lymphoepithelioid variant of PTCL-NOS

Also known as ‘Lennert lymphoma’, this is characterised by an abundant background of epithelioid histiocytes which may obscure the neoplastic lymphoid cells and may be associated with a better prognosis than other PTCL-NOS.97 The infiltrate is usually diffuse or less commonly interfollicular. The neoplastic cells are small slightly atypical CD8+ cytotoxic T cells.82 RS-like B cells, eosinophils and plasma cells are also commonly seen.

Best Regards
Sarah Jhonson
Managing Editor
International Journal of Case Reports
Email: caserep@emedicalsci.org