Gamma/Delta (γδ) T Cells: The Role of the T-Cell Receptor in Diagnosis and Prognosis of Hematologic Malignancies

Navigating Diagnostic and Therapeutic Challenges in Primary Cutaneous Gamma/Delta T-Cell Lymphoma: A Case Study of Fatal Outcomes Within Two Months

ABSTRACT

Primary cutaneous gamma/delta T-cell lymphoma (PCGD-TCL) is a rare yet highly aggressive subtype of primary cutaneous lymphoma. Characterized by its challenging diagnosis and poor prognosis, PCGD-TCL presents unique clinical and histopathological features that distinguish it from other primary cutaneous lymphoma subtypes. Here, we report the case of a 75-year-old man who initially presented with multiple erythematous indurated plaques over his back and bilateral lower extremities. The initial biopsy suggested primary cutaneous T-cell lymphoma (PCTCL) with a CD30-negative phenotype. However, within a 2-month interval, the disease progressed rapidly, manifesting as extensive skin involvement across the chest and upper extremities. A repeat skin biopsy was performed, revealing dermal atypical lymphocytes without epidermotropism. Immunohistochemical analysis demonstrated positivity for CD3, CD5, and CD4, as well as T-cell receptor delta (TCR delta) expression, along with the loss of CD8 and CD30 expression. These findings were consistent with a diagnosis of PCGD-TCL. Despite therapeutic interventions, including systemic treatments, the patient's condition deteriorated rapidly, ultimately leading to his demise within a month of receiving the PCGD-TCL diagnosis. This case highlights the diagnostic complexities associated with PCGD-TCL, emphasizing the importance of careful histopathological examination and immunophenotypic characterization. Given its aggressive nature and propensity for rapid dissemination, early recognition of PCGD-TCL is paramount for initiating appropriate therapeutic interventions. However, effective treatment options for PCGD-TCL remain limited, and the disease typically carries an unfavorable prognosis. Further research is needed to elucidate the underlying molecular mechanisms driving the pathogenesis of PCGD-TCL, to identify novel therapeutic targets, and to improve patient outcomes. In addition, increased awareness among clinicians and pathologists regarding the clinical presentation and diagnostic criteria of PCGD-TCL is crucial for facilitating timely diagnosis and management of this challenging malignancy.

Lymphomatoid Papulosis With T-cell Receptor-Gamma Delta Expression: A Clinicopathologic Case-series of 26 Patients of an Underrecognized Immunophenotypic Variant of Lymphomatoid Papulosis

Lymphomatoid papulosis (LyP) has several histopathologic presentations. LyP featuring gamma-delta (γδ) T-cell receptor expression may masquerade as and may be misdiagnosed as aggressive cutaneous T-cell lymphoma, particularly primary cutaneous γδ T-cell lymphoma (PCGDTL) or γδ mycosis fungoides. We performed a clinicopathologic analysis of the largest series of LyP featuring γδ T-cell expression. We identified 26 patients with a diagnosis of LyP with γδ T cells from our institutions, as well as through a comprehensive review of the literature, and characterized these cases. Most cases were treated with topical steroids or not treated at all. The majority of cases showed a CD4 - CD8 + phenotype and featured at least one cytotoxic marker. Histopathologic features included an intraepidermal or dermal infiltrate with large cells and frequent angiotropism. One case was initially misdiagnosed as PCGDTL, requiring further therapy. Our case series, the largest international cohort of γδ T cell predominant LyP cases, confirms marked clinicopathologic heterogeneity that may contribute to misdiagnosis, reasserting the need to identify classic clinical features, CD30 + T-cell components, and markers of cytotoxicity when dealing with this differential diagnosis. A limitation of this study includes somewhat limited follow-up, histologic, and immunophenotypic information for some cases.

Pediatric cutaneous T-cell neoplasm and mimics with gamma-delta expression: Not always aggressive

Pediatric cutaneous T-cell lymphoma with γδ immunophenotype is extremely rare. Only a few cases of γδ T-cell neoplasm have been reported in the literature, and therefore little is known whether γδ T-cell neoplasms in children are distinct from their adult counterparts with respect to the clinicopathological presentation, behavior, and prognosis. In this study, we demonstrate three unique pediatric cutaneous T-cell neoplasm and mimics with increased γδ T cells. All cases showed an indolent clinical course.

The intestinal γδ T cells: functions in the gut and in the distant organs

Located in the frontline against the largest population of microbiota, the intestinal mucosa of mammals has evolved to become an effective immune system. γδ T cells, a unique T cell subpopulation, are rare in circulation blood and lymphoid tissues, but rich in the intestinal mucosa, particularly in the epithelium. Via rapid production of cytokines and growth factors, intestinal γδ T cells are key contributors to epithelial homeostasis and immune surveillance of infection. Intriguingly, recent studies have revealed that the intestinal γδ T cells may play novel exciting functions ranging from epithelial plasticity and remodeling in response to carbohydrate diets to the recovery of ischemic stroke. In this review article, we update regulatory molecules newly defined in lymphopoiesis of the intestinal γδ T cells and their novel functions locally in the intestinal mucosa, such as epithelial remodeling, and distantly in pathological setting, e.g., ischemic brain injury repair, psychosocial stress responses, and fracture repair. The challenges and potential revenues in intestinal γδ T cell studies are discussed.

Identification of a potential novel biomarker in intervertebral disk degeneration by bioinformatics analysis and experimental validation

Background

Intervertebral disk degeneration (IVDD) is a major cause of low back pain and one of the most common health problems all over the world. However, the early diagnosis of IVDD is still restricted. The purpose of this study is to identify and validate the key characteristic gene of IVDD and analyze its correlation with immune cell infiltration.

Methods

3 IVDD-related gene expression profiles were downloaded from the Gene Expression Omnibus database to screen for differentially expressed genes (DEGs). Gene Ontology (GO) and gene set enrichment analysis (GSEA) were conducted to explore the biological functions. Two machine learning algorithms were used to identify characteristic genes, which were tested to further find the key characteristic gene. The receiver operating characteristic curve was performed to estimate the clinical diagnostic value of the key characteristic gene. The excised human intervertebral disks were obtained, and the normal nucleus pulposus (NP) and degenerative NP were carefully separated and cultured in vitro. The expression of the key characteristic gene was validated by real-time quantitative PCR (qRT-PCR). The related protein expression in NP cells was detected by Western blot. Finally, the correlation was investigated between the key characteristic gene and immune cell infiltration.

Results

A total of 5 DEGs, including 3 upregulated genes and 2 downregulated genes, were screened between IVDD and control samples. GO enrichment analysis showed that DEGs were enriched to 4 items in BP, 6 items in CC, and 13 items in MF. They mainly included the regulation of ion transmembrane transport, transporter complex, and channel activity. GSEA suggested that the cell cycle, DNA replication, graft versus host disease, and nucleotide excision repair were enriched in control samples, while complement and coagulation cascades, Fc γ R-mediated phagocytosis, neuroactive ligand-receptor interaction, the NOD-like receptor signaling pathway, gap junctions, etc., were enriched in IVDD samples. Furthermore, ZNF542P was identified and tested as key characteristic gene in IVDD samples through machine learning algorithms and showed a good diagnostic value. The results of qRT-PCR showed that compared with normal NP cells, the expression of ZNF542P gene was decreased in degenerated NP cells. The results of Western blot suggested that compared with normal NP cells, the expression of NLRP3 and pro Caspase-1 was increased in degenerated NP cells. Finally, we found that the expression of ZNF542P was positively related to the proportions of T cells gamma delta (γδT cells).

Conclusion

ZNF542P is a potential biomarker in the early diagnosis of IVDD and may be associated with the NOD-like receptor signaling pathway and the infiltration of γδT cells.

Coincidence of de novo T-lymphoblastic lymphoma and cutaneous gamma/delta peripheral T-cell lymphoma

The coincidence of acute T-lymphoblastic leukemia/lymphoma, NOS (T-ALL/LBL), and peripheral T-cell lymphoma (PTCL) is unusual, and there have only been a few cases of their metachronous occurrence. In these cases, PTCLs emerged as recurrence after primary therapy for primary T-ALL, were the rare gamma/delta type, and uncommonly involved skin for T-ALL/LBL. We herein report the first case of de novo T-LBL that coincided with cutaneous gamma/delta PTCL before primary therapy. A 70-year-old man presented with systemic lymphadenopathy. Lymph node biopsy revealed a massive proliferation of lymphoblastoid cells; immunohistochemically, they were positive for TdT/CD1a/CD99, and cytoplasmic CD3ε, CD4, and CD8 and were negative for T-cell receptor (TCR) βf-1. A few TCRδ-positive cells were intermingled. Atypically, TIA was focally positive, whereas granzyme/perforin was negative. Multiple papules and plaques emerged on the trunk before the initiation of treatment for T-LBL. Skin biopsy revealed a massive proliferation of medium-to-large atypical lymphoid cells that were TdT/CD1a-negative mature T-cells; they were negative for TCRβf1 and CD4, and positive for TCRδ, CD5, CD8, CD56, TIA, granzyme B, and perforin. A conventional PCR analysis of TCRG showed no identical clonal band between the two tumors. The skin lesion was diagnosed as cutaneous gamma/delta T-cell lymphoma. Whether the lesion was primary or a transformation of T-LBL was unclear. After treating with reduced hyper-CVAD/MA targeting T-LBL, molecular complete remission was achieved. When an uncommon cutaneous lesion emerges in the course of T-ALL/LBL, both need to be evaluated pathologically and genetically, whether de novo or recurrent, assuming the possibility of coincident gamma/delta PTCL.