Table 2 Current diagnostic challenges in T-cell lymphomas
From: MicroRNA expression signature as a biomarker in the diagnosis of nodal T-cell lymphomas
Diagnostic parameter | Supportive features of T-cell lymphoma | Limitations and Pitfalls |
|---|---|---|
Morphology | â–ª Architectural effacement | â–ª RLH can have architectural alterations (marked interfollicular expansion) that resemble T-cell lymphomas. â–ª Some T-cell lymphomas exhibit minimal changes to tissue architecture that can be similar to those seen in reactive hyperplasia. |
â–ª Cytological atypia | â–ª Cytologic atypia, particularly in nTFHL, may be minimal and display overlapping features with reactive T-cell proliferation. â–ª On the other hand, certain reactive lymph node conditions may present with increased numbers of large nucleolated (immunoblastic) cells that can be mistaken as neoplastic infiltrate. | |
Immunophenotype | â–ª Aberrant T-cell immunophenotype, i.e., lost, or reduced expression of T-cell antigens. â–ª Aberrant pattern of expression of normal physiological markers e.g., CD30, TFH markers (PD1, ICOS, CXCL13) etc. | â–ª Some T-cell lymphomas (particularly nTFHL) may retain full expression of T-cell antigens. â–ª Difficulty to interpret staining in small biopsy samples. â–ª Significant inter- and intra-observer variability. â–ª Quality of lab processing and IHC protocol will significantly affect results. â–ª A good understanding of protein biology and expression pattern is required for accurate interpretation. |
Clonality | â–ª Monoclonal TCRB or TCRG gene rearrangements in T-cell lymphomas. | â–ª Monoclonal TCRB or TCRG rearrangements may be detected in reactive T-cell proliferations, for example in viral infections. â–ª Conversely, false negativity can occur in some T-cell lymphomas with significant reactive inflammatory background, and in small biopsy samples with low volume of neoplastic T-cells. |