The K9 lymphoma assay allows a genetic subgrouping of canine lymphomas with improved risk classification.

We present here the K9 lymphoma assay, a novel 31-gene targeted next-generation sequencing panel designed for genomic profiling of canine lymphoid neoplasms. Addressing the growing demand for advanced diagnostics in veterinary oncology, this assay enables sensitive identification of known and actionable mutations specific to canine lymphomas, while evaluating its prognostic potential to facilitate diagnosis and prognosis. Our analysis, spanning several B- and T-cell lymphoma histotypes, unveiled distinct mutational landscapes distinguishing tumors derived from immature versus mature lymphocytes. Clustering analysis revealed a shared genetic origin between diffuse large B-cell lymphoma and marginal zone lymphoma, aligning with findings in human lymphomas, with TRAF3 emerging as the most frequently mutated gene across B-cell lymphoma subtypes. Significantly, TP53 mutations demonstrated universal adverse prognostic implications across B-cell lymphomas. Additionally, SETD2 mutations contributed to shorter time-to-progression, underscoring the role of epigenetic dysregulation in B-cell tumors. In T-cell lymphomas, SATB1 and FBXW7 were frequently mutated, warranting further investigation in larger cohorts. Our findings advocate for tailored therapeutic approaches based on the genetic profile, impacting treatment decisions and outcomes in canine lymphoma management. This study provides pivotal insights bridging veterinary and human oncology, paving the way for comprehensive genomic diagnostics and therapeutic strategies in comparative oncology.

Paws and Pathogens: A Multidisciplinary Approach Through Bartonella henselae Endocarditis and Hepatosplenic T-Cell Lymphoma.

Bartonella species are gram-negative coccobacilli that are globally recognized as significant pathogens causing zoonotic infections. Among Bartonella species, B. henselae, B. quintana, and B. bacilliformis are prominent pathogens causing infections in humans, often manifesting as infective endocarditis. Bartonella endocarditis can pose diagnostic challenges due to its indolent presentation and limitations of standard microbiological culture techniques to identify the organism. We report a case of a 23-year-old male, who initially presented with the manifestations of hepatosplenic T-cell lymphoma, later diagnosed with blood culture-negative endocarditis caused by B. henselae. The patient had a complicated clinical course including pancytopenia, hepatosplenomegaly, and severe aortic valve regurgitation. Despite negative blood cultures, diagnostic clues included persistent fevers and bicuspid aortic valve with abscess. High Bartonella IgG titers (>1:800) supported the diagnosis. This case underscores the importance of considering Bartonella species in patients with suspected endocarditis, particularly in those with predisposing factors and negative blood cultures. Diagnosis relies heavily on serologic assays due to low sensitivity of conventional culture methods. Treatment involves a multidisciplinary approach with antibiotics and surgical intervention for optimal outcomes. Timely recognition and management are crucial to mitigate the high mortality associated with Bartonella endocarditis, and we hope this article offers insight for clinicians.

The diagnostic relevance of mesenteric lymph node biopsy in small intestinal lymphoma in cats.

BACKGROUND: Regional lymph nodes are frequently sampled in cats with suspected intestinal lymphoma; however, their diagnostic value has not been explored. OBJECTIVES: To investigate whether histologic and immunohistochemical analysis of mesenteric lymph nodes correlates with the diagnosis of intestinal lymphoma in cats. ANIMALS: One hundred 2 client-owned cats diagnosed with intestinal lymphoma. METHODS: Retrospective study. The inclusion criteria required a full-thickness biopsy of the small intestine and concurrent excision of mesenteric lymph nodes. Histologic and immunophenotypic analyses were performed on intestinal biopsies and corresponding lymph nodes. Selected nodal samples diagnosed with reactive lymph nodes underwent clonality testing. RESULTS: Transmural T-cell lymphomas, encompassing small and large cell types, were predominant (64 cases, 62.7%), with large B-cell lymphomas being more frequently transmural (68.8%) than mucosal (31.2%). Among all lymph nodes examined, 44 (43.1%; 95% CI: 33.9%-52.8%) exhibited neoplastic infiltration. Among cases of small cell lymphoma, 51 out of 72 (70.8%; 95% CI: 59.4%-80.1%) showed no nodal involvement. Clonality results correctly identified 19/30 (63.3%; 95% CI: 45.5%-78.2%) reactive lymph nodes. Concerns were raised regarding clonal identification in the remaining cases and potential misdiagnoses based on phenotypic characteristics. CONCLUSION AND CLINICAL IMPORTANCE: The study underscores the potential drawbacks of relying solely on mesenteric lymph nodes for diagnosing intestinal lymphomas in cats, particularly small cell subtypes. It emphasizes the importance of full-thickness biopsies for assessing transmural infiltration and recommends caution when utilizing mesenteric lymph nodes for histologic, immunohistochemical and clonality evaluations in mucosal lymphomas. Despite limitations, this research highlights the need for comprehensive diagnostic strategies in cats with intestinal lymphoma.

Intestinal T-cell lymphomas NOS presenting as a polypoidal lesion: A case report.

RATIONALE: Intestinal T-cell lymphomas are exceedingly rare diseases. Intestinal T-cell lymphoma NOS, as a "wastebasket" category, is difficult to diagnosis. Endoscopy can identify abnormal mucosa in most patients at a reasonably early stage. Therefore, it is crucial to increase the understanding of endoscopists in terms of the endoscopic characteristics of ITCL. PATIENT CONCERNS: A 74-year-old male alone with wasting as the major complaint, had multiple polypoid lesions in the large intestine. The patient then had endoscopic care. DIAGNOSES: Only 1 polypoid lesion on white-light endoscopy in the sigmoid colon was pathologically diagnosed as intestinal T-cell lymphomas, not otherwise specified (ITCL-NOS). INTERVENTIONS: The patient underwent intensity-reduced CHOP therapy. OUTCOMES: The patient is still with controlled disease but developed chemotherapy-related side effects. LESSONS: In the individual with unexplained anemia and waste, endoscopy should not be delayed. For each of polypoid lesion on white-light endoscopy, the endoscopist need to remain cautious, because every lesion in the same patient can exhibit the independence of histopathological features. Meanwhile, we suggest that endoscopists should routinely observe the terminal ileum, even take biopsy samples if necessary.

Diagnosis of renal lymphoma by Wright-Giemsa-stained cytocentrifuged urine evaluation in a cat.

Lymphoma represents up to 30% of neoplasms diagnosed in cats. Diagnosis of lymphoma in the urinary system by examination of urine sediment has been described in a dog, but apparently not previously in cats. Concurrent samples of serum, EDTA whole blood, and urine were submitted from a 15-year-old spayed female domestic shorthair cat exhibiting weight loss, polyuria, and polydipsia. Hematology and biochemical abnormalities included a mild normocytic, normochromic, non-regenerative anemia; an inflammatory leukogram; and azotemia. Urinalysis evaluation revealed inadequate urine concentration and marked proteinuria. Wet-mount urine sediment examination revealed moderate numbers of leukocytes and erythrocytes. A uniform population of intermediate-to-large lymphocytes was observed on a fresh, Wright-Giemsa-stained preparation from cytocentrifuged urine. The cat was euthanized and necropsy was completed. Bilateral renomegaly was identified and characterized by multifocal, pale-yellow, coalescing, poorly defined, homogenous nodules. Microscopically, these nodules were composed of dense sheets of CD3-positive round cells, consistent with T-cell renal lymphoma. Key clinical message: Lymphoma is a common neoplasm in cats that can affect many organ systems, including the upper urinary tract. This case represents an uncommon method of identifying neoplastic lymphocytes via evaluation of cytocentrifuged urine, and emphasizes the benefits of examining Romanowsky-stained urine sediment in animals.

Diagnostic du lymphome rénal chez un chat par évaluation d'urine cytocentrifugée avec coloration Wright-Giemsa. Le lymphome représente jusqu'à 30 % des néoplasmes diagnostiqués chez le chat. Le diagnostic d'un lymphome du système urinaire par examen des sédiments urinaires a été décrit chez un chien, mais apparemment pas à ce jour chez le chat. Des échantillons simultanés de sérum, de sang total dans un tube avec EDTA et d'urine ont été soumis provenant d'une chatte domestique à poils courts stérilisée de 15 ans présentant une perte de poids, une polyurie et une polydipsie. Les anomalies hématologiques et biochimiques comprenaient une légère anémie normocytaire, normochrome et non régénérative; une formule leucocytaire inflammatoire; et une azotémie. L'analyse d'urine a révélé une concentration urinaire insuffisante et une protéinurie marquée. L'examen microscopique des sédiments urinaires a révélé un nombre modéré de leucocytes et d'érythrocytes. Une population uniforme de lymphocytes de taille intermédiaire à grande a été observée sur une préparation fraîche colorée au Wright-Giemsa à partir d'urine cytocentrifugée. Le chat a été euthanasié et une autopsie a été réalisée. Une rénomégalie bilatérale a été identifiée et caractérisée par des nodules multifocaux, jaune pâle, coalescents, mal définis et homogènes. Au microscope, ces nodules étaient composés de feuilles denses de cellules rondes CD3-positives, compatibles avec un lymphome rénal à cellules T.Message clinique clé :Le lymphome est une tumeur courante chez le chat qui peut affecter de nombreux systèmes organiques, y compris les voies urinaires supérieures. Ce cas représente une méthode rare d'identification des lymphocytes néoplasiques via l'évaluation de l'urine cytocentrifugée et met l'emphase sur les avantages de l'examen des sédiments urinaires avec coloration de Romanowsky chez les animaux.(Traduit par Dr Serge Messier).

Subcutaneous Panniculitis-like T Cell Lymphoma Diagnosed with a Slowly Progressive Course: A Case Report.

Panniculitis is an inflammation that occurs in subcutaneous adipose tissue. Panniculitis includes physical panniculitis (e.g., traumatic) and infectious panniculitis (e.g., bacterial, fungal, subcutaneous panniculitis-like T cell lymphoma [SPCTL], etc.). Accurate diagnosis is crucial due to similar clinical presentation of all types of panniculitis. Here, we report a case of SPCTL which was initially diagnosed with traumatic panniculitis. A 15-year-old male patient was admitted to a previous hospital due to a progressively enlarged right flank and inguinal mass after an abdominal bruise. He was initially diagnosed with traumatic panniculitis, but the mass expanded throughout the chest and abdomen accompanied by a fever of over 11 months. Computed tomography (CT) revealed a subcutaneous mass in the anterior chest and abdominal wall. Fludeoxyglucose F18 (FDG) uptake was observed at those lesions using FDG-positron emission tomography (PET). A biopsy of the mass lesion was performed, during which SPCTL was diagnosed based on pathological examination. He was initially treated with prednisolone and cyclosporine A for two weeks. His fever went down, but subcutaneous mass in the chest and abdominal wall persisted. Therefore, he received a cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) regimen. After 6 courses of CHOP, CT revealed no disease evidence. He remained in complete remission at 30 months of therapy.

Subcutaneous panniculitis-like T-cell lymphoma and lupus erythematosus profundus: a diagnostic dilemma.

A white Caucasian woman in her 30s presented with an indurated lesion on her right upper arm. Panniculitis was clinically suspected. Antinuclear antibody testing was positive but incisional biopsy showed subcutaneous panniculitis-like T-cell lymphoma (SPTCL), although with some unusual features more in keeping with lupus. Initial treatment was with oral prednisolone and radiotherapy but with only partial response. A second biopsy was taken from an area of presumed residual disease. This displayed histological features that were much more typical of lupus erythematosus profundus (LEP) but with tiny foci suggesting concomitant microscopic areas of SPTCL. Immunofluorescence for IgM was positive. This case highlights the rare occurrence of a patient with overlapping clinical and pathological features of SCPTL and LEP. It emphasises the need for close clinicopathological correlation in the workup of patients with suspected panniculitis and the importance of careful pathological examination for features of both diseases.

A case of equine multicentric lymphoma: Clinical, microscopical, and molecular findings.

Background: Although relatively uncommon, lymphoma is the most prevalent haematopoietic neoplasia in horses, and multicentric lymphoma remains the most common presentation of the disease. The pathogenesis of equine lymphoma is still poorly understood and the diagnosis is usually confirmed at an advanced stage of the disease, compromising the prognosis. This study investigated the clinical, pathological, and molecular features of a case of equine multicentric lymphoma. Case Description: An apparently healthy 5-year-old crossbreed mare hospitalized at the Centre of Animal Reproduction of Vairão, Portugal, suddenly presented clinical signs of supraorbital oedema and mandibular lymph node enlargement, developing fever, facial oedema, and generalized lymphadenopathy. The mare ended up dying twenty-four days after the first clinical signs due to multisystem organ failure. Haematological and biochemical analyses, necropsy, and microscopic and molecular evaluation of affected tissues were performed. At necropsy, the main findings were multiple multinodular lesions, distributed along the serous surface of oropharynx, trachea, pericardium, gastrointestinal tract, and mesentery. Microscopically, these consisted of solid proliferations of neoplastic round cells that exhibited immunopositivity for CD3 (T cells). Based on these findings, a medium-grade multicentric T-cell lymphoma was diagnosed. Conclusion: There is still very little research regarding the molecular characterization of lymphoma in horses. As an entity itself is quite heterogeneous, it is important to describe the interspecies particularities to understand its development and behaviour.

The CNS relapse in T-cell lymphoma index predicts CNS relapse in patients with T- and NK-cell lymphomas.

ABSTRACT: Little is known about risk factors for central nervous system (CNS) relapse in mature T-cell and natural killer cell neoplasms (MTNKNs). We aimed to describe the clinical epidemiology of CNS relapse in patients with MTNKN and developed the CNS relapse In T-cell lymphoma Index (CITI) to predict patients at the highest risk of CNS relapse. We reviewed data from 135 patients with MTNKN and CNS relapse from 19 North American institutions. After exclusion of leukemic and most cutaneous forms of MTNKNs, patients were pooled with non-CNS relapse control patients from a single institution to create a CNS relapse-enriched training set. Using a complete case analysis (n = 182), including 91 with CNS relapse, we applied a least absolute shrinkage and selection operator Cox regression model to select weighted clinicopathologic variables for the CITI score, which we validated in an external cohort from the Swedish Lymphoma Registry (n = 566). CNS relapse was most frequently observed in patients with peripheral T-cell lymphoma, not otherwise specified (25%). Median time to CNS relapse and median overall survival after CNS relapse were 8.0 and 4.7 months, respectively. We calculated unique CITI risk scores for individual training set patients and stratified them into risk terciles. Validation set patients with low-risk (n = 158) and high-risk (n = 188) CITI scores had a 10-year cumulative risk of CNS relapse of 2.2% and 13.4%, respectively (hazard ratio, 5.24; 95% confidence interval, 1.50-18.26; P = .018). We developed an open-access web-based CITI calculator (https://redcap.link/citicalc) to provide an easy tool for clinical practice. The CITI score is a validated model to predict patients with MTNKN at the highest risk of developing CNS relapse.

A new mode for the diagnosis of angioimmunoblastic T-cell lymphoma.

In order to explore a new mode for the diagnosis of angioimmunoblastic T-cell lymphoma (AITL), 31 cases of AITL and 28 cases of peripheral T-cell lymphoma, not otherwise specified (PTCL-NOS) were used as the study subjects. Identifying T follicular helper (TFH) cells with CD4, CD10, Bcl-6, and PD-1, identifying proliferative B cells with CD20 and EZH2, identifying proliferative follicular dendritic cells (FDCs) with CD21 and CD23, and analyzing the value of TFH/B/FDC proliferation and immunolocalization in the diagnosis of AITL. (1) Outside the inherent lymphoid follicles, simultaneous proliferation of TFH/B/FDC (a new diagnostic mode) were observed in AITL [83.87%; 26/31], with their immunolocalizations in the same site [83.87%; 26/31], while this phenomenon was not observed in 28 cases of PTCL-NOS (P<0.05). (2) The sensitivity and specificity of using this new mode to diagnose AITL were both high (83.87%, 100%), which was superior to CD2 (100%, 0%), CD3 (100%, 0%), CD4 (100%, 32.14%), CD5 (100%, 25%), CD10 (61.9%, 100%), Bcl-6 (42.86%, 100%), PD-1 (83.87%, 96.43%), and its Youden Index (0.84) was the highest. The areas under the curve (AUC) of CD10, Bcl-6, PD-1, and new mode to diagnosis AITL were 0.81, 0.71, 0.90, and 0.92, respectively, while the new mode had the highest AUC. The simultaneous proliferation of TFH/B/FDC cells outside the inherent lymphoid follicles can be used to assist in the diagnosis of AITL, and the simultaneous spatiotemporal proliferation of TFH/B/FDC cells is a specific immunomorphology of AITL.

Prognostic role of the updated Kiel classification in canine high-grade T-cell lymphomas.

BACKGROUND: The aim of this study was to determine and describe the prognostic role of the morphological subtype determined according to the updated Kiel classification in dogs with high-grade T-cell lymphomas (HGTCLs) depending on the treatment applied. OBJECTIVES: The HGTCLs were classified into three subtypes according to the updated Kiel classification: pleomorphic mixed (PM), lymphoblastic lymphoma/acute lymphoblastic leukaemia and plasmacytoid (P). The treatment was divided into a palliative therapy (PlT) group and a chemotherapy (ChT) group. METHODS: The study was conducted between 2009 and 2017, and it enrolled 58 dogs in which cytomorphological and immunocytochemistry diagnoses were HGTCL. RESULTS: Overall survival (OS) was significantly longer in the ChT group (median OS-4 months, interquartile range [IQR] from 2 to 8 months) than in the PlT group (median OS-6 weeks, IQR from 1 week to 3 months). In the PlT group, PM subtype and glucocorticosteroids (GCSs) treatment proved significantly and independently linked to longer OS and approximately three-fold lower risk of death during the study period (adjusted hazard ratio [HRadj] = 0.26, confidence interval [CI] 95%: 0.08-0.81; p = 0.020 and HRadj = 0.30, CI 95%: 0.11-0.77; p = 0.013, respectively), although due to small group size, precision of estimations was poor (wide CI 95%). In the ChT group, >7 days elapsing between diagnosis and the beginning of chemotherapy and GCS treatment prior to chemotherapy were significantly associated with lower chance of complete remission (CR; p = 0.034 for both); GCS treatment prior to chemotherapy was significantly associated with shorter OS (p = 0.016); chemotherapy based on the modified CHOP protocol was significantly associated with higher chance of CR (p = 0.034) and longer OS (p = 0.039); and CR was significantly linked to longer OS (p = 0.001). CLINICAL SIGNIFICANCE: The morphological subtype of HGTCL has some prognostic value in dogs treated palliatively (with PM subtype associated with longer OS than P subtype); however, this effect is no longer visible when a dog is treated with chemotherapy.

Subcutaneous Panniculitis-Like T-Cell Lymphoma With Hemophagocytic Lymphohistiocytosis.

Subcutaneous panniculitis-like T-cell lymphoma (SPTLP), a unique variant of primary cutaneous T-cell lymphomas, clinically mimics subcutaneous panniculitis. It is typified by the development of multiple plaques or subcutaneous erythematous nodules, predominantly on the extremities and trunk. Epidemiological findings reveal a greater incidence in females than males, affecting a wide demographic, including pediatric and adult cohorts, with a median onset age of around 30 years. Diagnosis of SPTLP is complex, hinging on skin biopsy analyses and the identification of T-cell lineage-specific immunohistochemical markers. Treatment modalities for SPTLP are varied; while corticosteroids may be beneficial initially for many patients, a substantial number require chemotherapy, especially in cases of poor response or relapse. Generally, SPTLP progresses slowly, yet approximately 20% of cases advance to hemophagocytic lymphohistiocytosis (HLH), often correlating with a negative prognosis. We report a case of a young male patient presenting with prolonged fever, multiple skin lesions accompanied by HLH, a poor clinical course, and eventual death, diagnosed postmortem with SPTLP. In addition, we also present a literature review of the current evidence of some updates related to SPTLP.

Diagnosis of bone marrow involvement in angioimmunoblastic T-cell lymphoma should be based on both [18F]FDG-PET/CT and bone marrow biopsy findings.

OBJECTIVE: During the initial staging of certain lymphoma subtypes, 18 F-fluorodeoxyglucose positron emission tomography/computed tomography ([18F]FDG-PET/CT) has become an alternative to bone marrow biopsy (BMB) for detecting bone marrow (BM) involvement. However, whether [18F]FDG-PET/CT can accurately detect BM involvement in angioimmunoblastic T-cell lymphoma (AITL) remains unknown. Our study aimed to assess the diagnostic and prognostic capability of [18F]FDG-PET/CT for detecting BM involvement in AITL. Methods: This retrospective study included 84 individuals newly diagnosed with AITL who underwent baseline BMB and [18F]FDG-PET/CT. "BM involvement" was defined as one or both of the following: 1) angioimmunoblastic T-cells detected in the BM; or 2) initially heightened focal uptake having disappeared on follow-up [18F]FDG-PET/CT. The ability of [18F]FDG-PET/CT to detect BM cancerous lesions was respectively analyzed by BM involvement confirmed by BMB or the aforementioned definition as the reference standard. The patients' clinical characteristics and survival and prognostic outcomes were respectively analyzed. RESULTS: Of the 84 participants, five (6.0%) displayed positive BMB and PET/BM results, 17 (20.2%) had BMB-positive but PET/BM-negative results, eight (9.5%) showed BMB-negative but PET/BM-positive outcomes, and 54 (64.3%) displayed negative BMB and PET/BM outcomes. Using pre-defined BM involvement as the reference standard, [18F]FDG-PET/CT exhibited a specificity of 100%, sensitivity of 40%, negative predictive value (NPV) of 75%, and positive predictive value (PPV) of 100%. In contrast, using BMB-detected BM involvement as reference, [18F]FDG-PET/CT exhibited a sensitivity, specificity, PPV, and NPV of 38.5%, 76.1%, 22.7%, and 87.1%, respectively. Among patients with PET/BM-positive and BMB-negative outcomes, 62.5% (5/8) underwent upstaging from III to IV. In 58.8% (10/17) of patients who were initially diagnosed with stage II/III disease based on the [18F]FDG-PET/CT results, repeat BMB resulted in upstaging to IV. PET/BM-negative patients had a higher 3-year progression-free survival rate (38.3% vs. 22.8%, p = 0.018) and 3-year overall survival rate (64.4% vs. 34.6%, p = 0.011) than PET/BM-positive patients. CONCLUSION: In AITL patients, PET/BM-positive results may obviate the necessity for repeat BMB to ascertain confirm BM involvement. PET/BM-negative results do not definitively exclude BM involvement. The combined use of [18F]FDG-PET/CT and BMB can increase the diagnostic accuracy of BM involvement for AITL patients.

Subcutaneous panniculitis-like T-cell lymphoma: fever and facial swelling with hemophagocytic syndrome.

We report a case of subcutaneous panniculitis-like T-cell lymphoma (SPTCL) in a young man presenting with fever and facial swelling. He had pancytopenia and hemophagocytic syndrome (HPS) on evaluation. The histopathological examination of skin punch biopsy from the face and chest wall showed SPTCL. Given the associated HPS, he was started on steroid and multidrug chemotherapy following which he had symptomatic improvement.

Gamma-delta T-cell lymphoma of the central nervous system: A case report and review of the literature.

Primary T-cell lymphoma (TCL) of the central nervous system (CNS) is a rare and potentially aggressive entity. We describe a case of TCL presenting in the basal ganglia with γδ receptor expression and a remarkably aggressive clinical course. To the best of our knowledge, this is the fifth reported case of γδ TCL presenting in the CNS. We review existing literature, including the previously reported cases of γδ TCL of the CNS. In our case, a 69-year-old male presented with acute onset dysarthria and right-sided weakness, with initial imaging concerning for stroke. Repeat imaging demonstrated a 2.6-cm mass in the left basal ganglia-corona radiata. Pathologic examination of a stereotactic biopsy revealed TCL with γδ receptor phenotype. The patient suffered rapid clinical decline and passed away within 6 weeks of initial diagnosis. This represents an important differential diagnosis and sheds light on the potentially poor prognosis conferred by γδ TCL of the CNS.

Update on T-Cell Lymphoma Epidemiology.

PURPOSE OF REVIEW: T-cell lymphomas (TCLs) are a group of rare subtypes of non-Hodgkin lymphoma derived from mature T-lymphocytes. Recent updates in lymphoma classification based on the cell-of-origin pathogenesis have shed new light on TCL epidemiology and outcomes. Contemporary regional consortia and international studies, including those conducted recently in Asia and South America, have provided an updated delineation of the major subtypes across various global regions. RECENT FINDINGS: Peripheral T-cell lymphoma, not otherwise specified (PTCL-NOS), remains the most common subtype globally except in Asia, where extra-nodal NK-T cell lymphoma (ENKTL) has emerged as the most prevalent. Angioimmunoblastic T-cell lymphoma (AITL) is the second most common subtype globally except in South America where its incidence falls behind adult T-cell leukemia/lymphoma (ATLL) and ENKTL. ALK-negative anaplastic large cell lymphoma (ALCL) has been recognized as the second most common subtype in some parts of South America. Studies on the newly classified breast implant-associated ALCL (BIA-ALCL) are beginning to reveal its distribution and risk factors. Deciphering the epidemiology of TCLs is a challenging endeavor due to the rarity of these entities and ongoing refinement in classification. Collaborative efforts on prospective registries based on the most current WHO classifications will help capture the true epidemiology of TCL subtypes to better focus resources for diagnostic, prognostic, and therapeutic efforts.

Incidence trends for common subtypes of T-cell lymphoma in Taiwan and the United States from 2008-2020.

The incidence of T-cell lymphoma (TCL) has been continually increasing in Taiwan and the United States (US) in recent years. This epidemiological study using population-based registry data aimed to determine the incidence patterns of common subtypes of TCL in Taiwan from 2008-2020 and compare them with those in the US and the Asian/Pacific Islander (API) population. Subtypes included angioimmunoblastic T-cell lymphoma (AITL); extranodal NK/T-cell lymphoma, nasal or other type (ENKTL); peripheral T-cell lymphoma, not otherwise specified (PTCL-NOS); and anaplastic large cell lymphoma (ALCL). The total number of patients newly diagnosed with TCL during 2008-2020 was 4477, 3171, and 48,889 in Taiwan, API, and the US, respectively. Except the incidence rate of AITL in Taiwan, the incidence rates of these common TCL subtypes showed downward trends in all studied populations. There was also a significant increase in the relative frequency of AITL among TCL in Taiwan, with an annual percent change of 4.44 (p < 0.001), from 8.44% in 2002 to 20.63% in 2020. The rapid development of diagnostics may be the main factor contributing to this rise in incidence.

Angioimmunoblastic T-cell lymphoma involving the nasopharynx: An easily misdiagnosed disease with atypical histopathological features.

OBJECTIVES: To explore the clinicopathologic features, treatment, and survival outcomes of angioimmunoblastic T-cell lymphoma (AITL) involving the nasopharynx. METHODS: We retrospectively analyzed 73 cases of AITL. Among them, 64 cases with complete pre-treatment 18F-FDG positron emission tomography/computed tomography (PET/CT) images were integrated into the analysis of clinical characteristics and PET/CT findings of AITL involving the nasopharynx; 14 cases with both biopsies from lymph node and nasopharynx were included in the comparison of pathological characteristics of AITL in the two areas. Forty-six of the 73 patients who received first-line systemic treatment at our institute were included in the treatment efficacy and survival analyses. RESULTS: Nasopharyngeal involvement was seen in 44/64 (68.8%) patients. Histologically, lymph node and nasopharyngeal biopsies in 14 patients both showed small to medium-sized tumor cells, complex inflammatory infiltration, and Reed-Sternberg-like cells or B immunoblasts. However, tumor cells with clear cytoplasm, significant high endothelial venule (HEV) hyperplasia, and perivascular infiltration were observed in 5/14, 3/14, and 2/14 nasopharyngeal biopsies, respectively, but in all fourteen lymph node biopsies (P < 0.05). Immunophenotypic profiles and gene rearrangements were highly concordant. Treatment efficacy and survival were similar between patients with nasopharyngeal involvement and those without (P > 0.05), indicating nasopharyngeal involvement is not a prognostic factor for AITL patients. CONCLUSIONS: Nasopharyngeal involvement is common in AITL but can be easily misdiagnosed because of its atypical pathologic pattern, especially when a lymph node biopsy is unavailable. However, the patient's clinical presentation, PET/CT manifestations, the typical immunophenotype, and gene rearrangements help the diagnosis.