A difficult case of angioimmunoblastic T-cell lymphoma to diagnose

Angioimmunoblastic T-cell lymphoma and correlated neoplasms with T-cell follicular helper phenotype: from molecular mechanisms to therapeutic advances

Angioimmunoblastic T-cell lymphoma (AITL) is the second most frequent subtype of mature T-cell lymphoma (MTCL) in the Western world. It derives from the monoclonal proliferation of T-follicular helper (TFH) cells and is characterized by an exacerbated inflammatory response and immune dysregulation, with predisposition to autoimmunity phenomena and recurrent infections. Its genesis is based on a multistep integrative model, where age-related and initiator mutations involve epigenetic regulatory genes, such as TET-2 and DNMT3A. Subsequently, driver-mutations, such as RhoA G17V and IDH-2 R172K/S promote the expansion of clonal TFH-cells ("second-hit"), that finally begin to secrete cytokines and chemokines, such as IL-6, IL-21, CXCL-13 and VEGF, modulating a network of complex relationships between TFH-cells and a defective tumor microenvironment (TME), characterized by expansion of follicular dendritic cells (FDC), vessels and EBV-positive immunoblasts. This unique pathogenesis leads to peculiar clinical manifestations, generating the so-called "immunodysplastic syndrome", typical of AITL. Its differential diagnosis is broad, involving viral infections, collagenosis and adverse drug reactions, which led many authors to use the term "many-faced lymphoma" when referring to AITL. Although great advances in its biological knowledge have been obtained in the last two decades, its treatment is still an unmet medical need, with highly reserved clinical outcomes. Outside the setting of clinical trials, AITL patients are still treated with multidrug therapy based on anthracyclines (CHOP-like), followed by up-front consolidation with autologous stem cell transplantation (ASCT). In this setting, the estimated 5-year overall survival (OS) is around 30-40%. New drugs, such as hypomethylating agents (HMAs) and histone deacetylase inhibitors (HDAi), have been used for relapsed/refractory (R/R) disease with promising results. Such agents have their use based on a biological rationale, have significant potential to improve the outcomes of patients with AITL and may represent a paradigm shift in the therapeutic approach to this lymphoma in the near future.

Limited Tissue Biopsies and Hematolymphoid Neoplasms

OBJECTIVES

Use of fine-needle aspiration/needle core biopsy (FNA/CNB) in evaluating hematolymphoid processes has been debated. We investigate its applicability in various clinicopathologic settings.

METHODS

We retrospectively analyzed 152 cases of FNA/CNB.

RESULTS

Of 152 FNA/CNBs, 124 (81.6%) resulted in diagnoses without excisional biopsies, while 28 required subsequent excisional biopsies. Of these, 43 FNA/CNBs performed for suspected lymphoma relapse demonstrated 95.4% diagnostic rate (41/43), which was significantly better than those without history of lymphoma (77/109, 71%; odds ratio [OR], 8.5; confidence interval, 1.9-37.4). Patients with immunodeficiency also showed a high rate of diagnosis by FNA/CNB (100%). When stratified by types of disease, diffuse large B-cell lymphoma/high-grade B-cell lymphoma demonstrated a higher success rate (92.7%) than small B-cell lymphoma (79.2%), though the difference was not statistically significant (OR, 3.3; P value = .07). A subsequent excisional biopsy was required in 28 cases, 23 of which resulted in diagnoses concordant with the FNA/CNB. Five cases showed diagnostic discordance, reflecting pitfalls of FNA/CNB in unusual cases with complex pathology.

CONCLUSIONS

FNA/CNB is practical in evaluating most hematolymphoid lesions, with high efficacy in recurrent disease and some primary neoplasms with homogeneous/ aggressive histology, or characteristic immunophenotype.