Aims: Thymic epithelial tumours (TET), including thymomas and thymic carcinomas and thymic neuroendocrine neoplasms, are malignant neoplasms that can be associated with morbidity and mortality. Recently, an updated version of the World Health Organization (WHO) Classification of Thoracic Tumours 5th Edition, 2021 has been released, which included various changes to the classification of these neoplasms. In addition, in 2017 the Union for International Cancer Control (UICC) / American Joint Committee on Cancer (AJCC) published the 8th Edition Staging Manual which, for the first time, includes a TNM staging that is applicable to thymomas, thymic carcinomas, and thymic neuroendocrine neoplasms. Methods and Results: To standardize reporting of resected TET and thymic neuroendocrine neoplasms the accrediting bodies updated their reporting protocols. The International Collaboration on Cancer Reporting (ICCR), which represents a collaboration between various National Associations of Pathology, updated its 2017 histopathology reporting guide on TET and thymic neuroendocrine neoplasms accordingly. This report will highlight important changes in the reporting of TET and thymic neuroendocrine neoplasms based on the 2021 WHO, emphasize the 2017 TNM staging, and also comment on the rigour and various uncertainties for the pathologist when trying to follow that staging. Conclusion: The ICCR dataset provides a comprehensive, standardized template for reporting of resected TET and thymic neuroendocrine neoplasms.

Primary gastrointestinal T/NK cell lymphoma (GI-TNKL) is an uncommon and heterogeneous group of lymphoid malignancies. We aimed to investigate their subtype distribution, clinicopathologic characteristics, and clinical outcomes. A total of 38 GI-TNKL cases and their clinical and pathological characteristics were analyzed. GI-TNKL occurred in adults with a median patient age in the sixth decade of life and showed a slight male predominance. The most common histologic type was extranodal NK/T-cell lymphoma, nasal type (ENKTL; 34.2%), followed by monomorphic epitheliotropic intestinal T-cell lymphoma (MEITL; 31.6%), intestinal T-cell lymphoma, NOS (ITCL, NOS, 18.4%), anaplastic large cell lymphoma, ALK-negative (ALCL, ALK-; 13.2%). The small intestine was the primary affected region. More than 90% of patients complained of various GI symptoms and cases with advanced Lugano stage, high IPI score, or bowel perforation that required emergent operation were not uncommon. GI-TNKL also showed aggressive behavior with short progression-free survival and overall survival. This thorough clinical and pathological descriptive analysis will be helpful for accurate understanding, diagnosis, and treatment.

Although MYC and BCL2 co-expression in diffuse large B cell lymphoma (DLBCL) is associated with inferior prognosis, it remains uncertain whether upfront autologous hematopoietic stem cell transplantation (ASCT) is beneficial in this lymphoma. This study aimed to investigate whether ASCT consolidation could have a positive role for patients with MYC and BCL2 co-expression (double-expressor lymphoma, DEL). We retrospectively evaluated 67 DLBCL patients who underwent upfront ASCT following rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone chemotherapy. The 5-year overall survival (OS) and progression-free survival (PFS) were 82.3% and 79.2%, respectively. There were 23 (34.3%) patients with DEL and 51 (76.1%) patients with non-germinal center B cell (GCB) subtype. The 5-year OS and PFS of patients with DEL were not different from those with non-DEL (P = 0.429 and P = 0.614, respectively). No survival difference for OS and PFS was also observed between GCB and non-GCB subtypes (P = 0.950 and P = 0.901, respectively). The OS and PFS were comparable for patients with DEL and non-DEL and both GCB and non-GCB subtypes. In conclusion, MYC and BCL2 co-expression did not have a poor prognostic impact among high-risk patients with DLBCL treated with upfront ASCT regardless of molecular classification. This preliminary study suggested that the role of consolidative ASCT is needed to be evaluated in a prospective randomized clinical trial.

Herein, we describe the first case of renal intravascular large B cell lymphoma in Korea occurring in a 66-year-old female. She presented with mild fever and dyspnea. On physical and laboratory evaluations, hemophagocytic lymphohistiocytosis was suspected, but the bone marrow biopsy results were unremarkable. During the work-up, massive proteinuria developed, which led to a renal biopsy. The renal architecture was relatively well-preserved, but the glomeruli were hypercellular with the infiltration of atypical, large lymphoid cells with increased nucleus-cytoplasm ratio and clumped chromatin. Similar cells were also present in the peritubular capillaries. The tumor cells exhibited membranous staining for CD20 and CD79a. After the diagnosis of intravascular large B cell lymphoma, the patient received rituximab-based chemotherapy under close follow-up.

The gastrointestinal (GI) tract is a prevalent site for extranodal lymphomas. Some subtypes of GI tract lymphomas are aggressive and have dismal clinical outcomes. Therefore, prompt histopathologic detection of such types can be very important. We thus introduce a practical approach in the histopathologic diagnosis of GI lymphomas according to the revised World Health Organization (WHO) classification. When lymphocyte proliferation is found in the GI tract, a stepwise approach can help narrow down the differential diagnoses. When considering subtype incidence, macroscopic findings, and microscopic patterns, applying a first-line marker battery of CD20, CD3, CD30, and Epstein-Barr virus–encoded RNAs can effectively narrow down the top differential diagnoses at the initial step. Generally, the most common subtype among GI tract lymphomas is B-cell non-Hodgkin lymphoma identified by CD20 expression, followed by T-cell and NK-cell non-Hodgkin lymphomas identified by the CD3 expression, and some subtypes are defined by Epstein-Barr virus infection or CD30 expression. Macroscopically, lymphomas present as various gross types, such as large masses, small lesions, superficial and shallow lesions, polyp-like or polyposis-like features, or ulcer/necrosis/perforation. Microscopically, large pleomorphic cells or small to medium-sized tumor cells grow with various architectures and tumor microenvironments. Incorporation of macroscopic and microscopic features and the stepwise immunophenotyping may be a practical approach to the differential diagnosis of aggressive lymphoma, indolent/low-grade lymphoma, or benign to indolent lymphoproliferative disease. Exceptions always exist; this approach focuses on the relatively prevalent circumstances of lymphomatous lesions initially encountered in the GI tract.

Purpose Histiocytic and dendritic cell neoplasms are rare hematologic tumors. This study aimed to describe the epidemiologic features of the entire spectrum of histiocytic and dendritic cell neoplasms, including clinicopathological variables and patient outcomes. Materials and Methods We comprehensively reviewed 274 patients who were diagnosed with histiocytic and dendritic neoplasms at Severance Hospital, Seoul, South Korea between 1995 and 2018. Results The most common neoplasm was Langerhans cell histiocytosis (LCH), followed by dermal xanthogranuloma. Among non-LCH sarcomas, histiocytic sarcoma (HS) showed a relatively high prevalence, followed by follicular dendritic cell sarcoma (FDCS). Disseminated juvenile xanthogranuloma (DJG), Erdheim-Chester disease (ECD), indeterminate dendritic cell tumor (IDCT), and interdigitating dendritic cell sarcoma (IDCS) rarely occurred. Generally, these tumors presented in childhood, although the non-LCH sarcoma (HS/FDCS/IDCS/IDCT) group of tumors and ECD occurred in late adulthood. Multiorgan involvement and advanced Ann-Arbor stage, as well as recurrence and death of disease, were not uncommon. The non-LCH sarcoma group had the worst overall survival, compared to the DJG, ECD, and LCH groups. Conclusion Our findings indicate that histiocytic and dendritic cell neoplasms exhibit heterogeneous epidemiologic characteristics and that some patients may have unfavorable outcomes, especially those with non-LCH sarcoma.

Background/Aims Although the use of surveillance 18F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) is discouraged in patients with diffuse large B-cell lymphoma, its usefulness in different subtypes has not been thoroughly investigated. Methods We retrospectively evaluated 157 patients who showed positive results on surveillance FDG-PET/CT every 6 months following complete response for up to 5 years. All of the patients also underwent biopsies. Results Seventy-eight (49.6%) of 157 patients had true positive results; the remaining 79 (50.3%), including eight (5.1%) with secondary malignancies, were confirmed to yield false positive results. Among the 78 patients with true positive results, the disease in seven (8.9%) had transformed to a different subtype. The positive predictive value (PPV) of FDG-PET/CT for aggressive B-cell non-Hodgkin’s lymphoma (NHL) was lower than that for indolent B-cell or aggressive T-cell NHL (p = 0.003 and p = 0.018, respectively), especially in patients with a low/low-intermediate international prognostic index (IPI) upon a positive PET/CT finding. On the other hand, indolent B-cell and aggressive T-cell NHL patients showed PPVs of > 60%, including those with low/low-intermediate secondary IPIs. Conclusions The role of FDG-PET/CT surveillance is limited, and differs according to the lymphoma subtype. FDG-PET/CT may be useful in detecting early relapse in patients with aggressive T-cell NHL, including those with low/low-intermediate risk secondary IPI; as already known, FDG-PET/CT has no role in aggressive B-cell NHL. Repeat biopsy should be performed to discriminate relapse or transformation from false positive findings in patients with positive surveillance FDG-PET/CT results.

Purpose Forkhead box C1 (FOXC1) is critical for maintaining bone marrow microenvironments during hematopoiesis, but its role in hematological malignancies remains obscure. Here, we investigated whether FOXC1 regulates tumor dormancy and activation in the microenvironments of T and natural killer (NK) cell lymphomas. Materials and Methods One hundred and twenty cases of T and NK cell lymphomas were included; the immunohistochemical expression of FOXC1 was investigated in stromal cells, and numbers of FOXC1(+) stromal cells were counted. Furthermore, the expression of phosphorylated p38 (p-p38) and phosphorylated ERK1/2 (p-ERK1/2) in tumor cells was investigated using immunohistochemistry. Results FOXC1 was variably expressed in C-X-C motif chemokine 12-associated reticular stromal cells, histiocytes, (myo)fibroblasts, and endothelial cells. The phenotypes of cases were categorized as dormant (high p-p38/low p-ERK1/2; n=30, 25.0%), active (high p-ERK1/2/low p-p38; n=25, 20.8%), or intermediate (others; n=65, 54.2%). Lower FOXC1(+ )stromal cell infiltration was associated with the dormant phenotype, the precursor T lymphoblastic leukemia/lymphoma subtype, and inferior overall survival rates, whereas higher FOXC1(+) stromal cell infiltration was associated with the active phenotype and favorable patient prognosis (p < 0.05 for all). Conclusion These results suggested that FOXC1(+) stromal cells within the microenvironments of T and NK cell lymphomas might be related to tumor phenotypes.

Primary effusion lymphoma (PEL) is a B-cell non-Hodgkin's lymphoma that is usually characterized by lymphomatous effusions in the body cavity without any detectable tumor masses. According to the World Health Organization (WHO) schema for tumor classification, PEL is defined by the presence of human herpesvirus 8 (HHV8) in malignant lymphoid cells. However, a subset of effusion-based B-cell lymphoma is not HHV8-positive and exhibits different clinicopathological characteristics. The 2017 WHO Classification of Tumors of Hematopoietic and Lymphoid Tissues does not list HHV8-negative effusion-based lymphoma, which remains an underappreciated B-cell lymphoma, as an individual entity. The present study reports a case of this rare type of lymphoma with indolent clinical behavior in a 75-year-old male patient receiving only symptomatic treatment. Additionally, a review of similar cases reported in the English literature is presented.

To determine the relative frequency and change of malignant lymphoma in Korea according to the 4th World Health Organization (WHO) classification and compare with previous reports. Between 2015 and 2016, 7737 new patients with malignant lymphoma were enrolled from 31 institutes, with their clinicopathologic information obtained, and evaluated for the relative frequency of lymphoma subtypes. The relative frequency of non-Hodgkin lymphoma (NHL) was 94.8%, and that of Hodgkin lymphoma (HL) was 5.2%. B cell lymphomas accounted for 83.1% of all NHLs; T/natural killer (NK) cell lymphomas, 16.4%; and immunodeficiency-associated lymphoproliferative disorders, 0.5%. The most common NHL subtypes were diffuse large B cell (41.5%), extranodal marginal zone (MALT, 19.8%), follicular (7.5%), NK/ T cell (4.2%), and peripheral T cell lymphomas, not otherwise specific (PTCL, NOS, 3.4%). Nodular sclerosis was the predominant HL subtype (48.5%), followed by mixed cellularity (28.7%), lymphocyte-rich (6.8%), lymphocyte-depleted (1.5%), lymphocyte-predominant (2.8%), and unclassified HL (11.8%). Compared with a previous report, increased B cell lymphomas (77.6–83.1%) and slightly decreased NK/T cell lymphomas and PTCL were observed. The incidence of follicular lymphoma increased by more than 2.5-fold (2.9–7.5%). Incidence rates of newly diagnosed lymphomas were lower for HL and higher for extranodal NHL, MALT, and nasal type NK/T cell lymphomas in Korea than those in Western countries. A slight increase in the relative frequency of B cell lymphoma and a prominent increase in follicular lymphoma may be attributed to refined diagnostic criteria and Westernized disease patterns.

Purpose The treatment outcome of brentuximab vedotin (BV) has not been related with CD30 expression in previous studies enrolling patients with a wide range of CD30 expression level. Thus, this study explored the efficacy of BV in high-CD30–expressing non-Hodgkin lymphoma (NHL) patients most likely to benefit. Materials and Methods This phase II study (Clinicaltrials.gov: NCT02280785) enrolled relapsed or refractory high-CD30–expressing NHL, with BV administered intravenously at 1.8 mg/kg every 3 weeks. The primary endpoint was > 40% disease control rate, consisting of complete response (CR), partial response (PR), or stable disease. We defined high CD30 expression as ≥ 30% tumor cells positive for CD30 by immunohistochemistry. Results High-CD30-expressing NHL patients (n=33) were enrolled except anaplastic large cell lymphoma. The disease control rate was 48.5% (16/33) including six CR and six PR; six patients (4CR, 2PR) maintained their response over 16 completed cycles. Response to BV and survival were not associated with CD30 expression levels. Over a median of 29.2 months of follow-up, the median progression-free and overall survival rates were 1.9 months and 6.1 months, respectively. The most common adverse events were fever (39%), neutropenia (30%), fatigue (24%), and peripheral sensory neuropathy (27%). In a post-hoc analysis for the association of multiple myeloma oncogene 1 (MUM1) on treatment outcome, MUM1-negative patients showed a higher response (55.6%, 5/9) than MUM1-positive patients (13.3%, 2/15). Conclusion BV performance as a single agent was acceptable in terms of disease control rates and toxicity profiles, especially MUM1-negative patients.

Adult-onset Still's disease (AOSD) is a rare systemic inflammatory disease manifesting with a persistent high-spiking fever, a typical rash, and lymphadenopathy. Endogenous factors related to interleukin-1, such as S100A8/A9 and several chemokines including CXCL10, CXCR3, and CXCL13, potentially play roles in its pathogenesis. We describe the histopathological features and chemokine expression pattern in lymph nodes (LNs) of patients with AOSD. Formalin-fixed, paraffin-embedded excisional LN tissues from 48 patients with AOSD were histologically reviewed. CXCL10, CXCR3, CXCL13, and S100A8/A9 expression was evaluated immunohistochemically. The pathology of LN was characterized by paracortical hyperplasia with proliferation of histiocyte, immunoblast, CD8-positive lymphoid cell and blood vessel. Most cases required differential diagnosis from dermatopathic lymphadenitis (n = 16, 33.3%), T cell lymphoma (n =11, 22.9%), and histiocytic necrotizing lymphadenitis (HNL) (n = 9, 18.8%). The expression levels of CXCL10 and CXCR3 were higher in patients with AOSD than in those with T cell lymphoma, HNL, tuberculous lymphadenitis, and reactive hyperplasia. It is important to recognize the aforementioned histopathologic findings of nodal involvement of AOSD because improper diagnosis and treatment can be avoided. Immunohistochemical staining for chemokines, CXCL10 and CXCR3, may aid in differentiating AOSD from other mimickers.

Dysregulated matrix metalloproteinase (MMP) gene expression is a major cause of the degradation of lung tissue that is integral to emphysema pathogenesis. Cigarette smoking (CS) increases MMP gene expression, a major contributor to emphysema development. We previously reported that Zbtb7c is a transcriptional repressor of several Mmp genes (Mmps-8, -10, -13, and -16). Here, we show that Zbtb7c knockout mice have mild emphysema-like phenotypes, including alveolar wall destruction, enlarged alveoli, and upregulated Mmp genes. Alveolar size and Mmp gene expression in Zbtb7c(-/-) mouse lungs are increased more severely upon exposure to CS, compared to those of Zbtb7c(+/+) mouse lungs. These observations suggest that Zbtb7c degradation or absence may contribute to the pathogenesis of emphysema.

Stored platelets undergo deleterious changes, referred to as platelet storage lesions (PSLs), which accelerate the desialylation of platelets and result in their phagocytosis and clearance by hepatic macrophages. Recent studies have reported that Ashwell–Morell receptor binds to desialylated platelets, thereby inducing hepatic thrombopoietin (TPO) production in a mouse model. Therefore, this study aimed to demonstrate these relationships between PSL and hepatic TPO production in human study.

Recently, various long non-coding RNAs (lncRNAs) have been reported to have significant therapeutic or prognostic value. However, the expression of lncRNAs has not been investigated in T and NK cell lymphoma. Thus, we evaluated the biological and prognostic role of lncRNAs related to the polycomb repressive complex (PRC) and PRC markers in tissue samples and cell lines of T and NK cell lymphoma. Among the tested lncRNAs, MALAT1 was most highly expressed in clinical samples and cell lines. High expression of MALAT1 as well as BMI1 was related to poor prognosis in patients with mature T cell lymphoma. In the tissue samples, BMI1 expression showed a positive correlation with EZH2, SUZ12, H3K27me3, and MALAT1. Multiple linear regression analysis showed that BMI1 expression was independently associated with H3K27me3. Direct binding of MALAT1 to the PRC2 components (EZH2 and SUZ12) was observed in a T cell lymphoma cell line; however, no direct binding of MALAT1 with H3K27me3 and BMI1 (a PRC1 component) was observed. In T and NK cell lymphomas, MALAT1 was related to poor prognosis. MALAT1 directly binds to EZH2 and SUZ12, and BMI1 activation may be induced possibly through H3K27me3.

As DNA databases continue to grow and international cooperation increases, forensic STR loci have expanded to increase the discriminatory power and inter-database compatibility. Current capillary electrophoresis (CE) and/or massively parallel sequencing (MPS)-based commercial STR analysis systems reflect such changing trends of expanding STR loci. Due to the general gains of larger multiplexing and the detection of sequence variation, the application of MPS technology to STR analysis has further improved discrimination and is expected to aid in mixture interpretation by increasing the effective number of alleles. However, high-throughput analysis has rarely been reported for forensic DNA databasing. In this study, we present the sequencing results from 250 Korean samples at 23 commonly used STR loci (D1S1656, TPOX, D2S441, D2S1338, D3S1358, FGA, CSF1PO, D5S818, D6S1043, D7S820, D8S1179, D10S1248, TH01, vWA, D12S391, D13S317, Penta E, D16S539, D18S51, D19S433, D21S11, Penta D, and D22S1045) using an in-house assay designed for MPS. All amplicons in the multiplex exhibited a size range of 77 to 217 base pairs, and the barcoded library for the MPS run was easily prepared using a PCR-based library preparation method followed by sequencing on a MiSeq System (Illumina). We compared the STR genotyping results with those obtained using CE and scrutinized the sequence variations in both the targeted STR and flanking regions. MPS results of 23 autosomal STRs were 99.97% concordant with those of CE results. D12S391 and D21S11 exhibited, respectively, the highest number of alleles and genotypes by the MPS analysis. Single nucleotide polymorphisms and insertion and deletions (Indels) were observed in the flanking regions of D1S1656, D2S441, D5S818, D7S820, D13S317, D16S539, D21S11, and Penta D. Consequently, an MPS analysis of an expanded set of STRs, as demonstrated in the population statistics of a Korean population, will be of great practical use in forensic genetics.

The goal of this study was to reassess serum alkaline phosphatase ( ALP ) as tumor marker in osteosarcoma. We retrospectively examined serum ALP levels at diagnosis, every therapeutic step (neoadjuvant chemotherapy, surgery, and adjuvant chemotherapy), metastasis, and follow‐up and analyzed the role of ALP as tumor marker in 210 osteosarcomas. The diagnostic performances of ALP were validated with pathology‐proven 899 other primary bone lesions. Elevated ALP at diagnosis was associated with inferior overall survival ( OS ) ( Log Rank P < 0.001) and disease‐free survival ( Log Rank P = 0.005) and independently significant for OS in multivariate analysis (hazard ratio [ HR ]=2.12, P = 0.032 ) . During therapy, the ALP level significantly changed according to therapeutic steps ( P < 0.001 for patients ≥15 years old , P < 0.001 for patients <15 years old) and survival ( P = 0.015 for ≥15 years , P = 0.002 for <15 years), and the response of ALP to therapy and survival were associated ( P = 0.042 for ≥15 years , P = 0.036 for <15 years). Initial ALP level was linearly correlated with tumor burden (total tumor volume; P = 0.016 for ≥15 years, bone tumor volume; P = 0.012 for ≥15 years). The sensitivity and specificity of ALP on diagnosis were 53.2% (95% Confidence Interval [ CI ]: 0.475–0.586) and 90.1% (95% CI : 0.888–0.913). The sensitivity of ALP on metastasis was 53.2% (95% CI : 0.431–0.624), and the specificity was 78.2% (95% CI : 0.720–0.839) at15 months postoperative and 90.0% (95% CI : 0.824–0.952) at 3 years postoperative. Serum ALP was found to be a valuable tumor marker with high specificity in osteosarcoma.

Muscle specific tyrosine kinase (MuSK) myasthenia gravis (MG) is a rare subtype of MG, which is immunologically distinct and differential therapeutic response. Though MG is often associated with other autoimmune disorders or malignancy, concurrence of other disease and MuSK MG has been infrequently reported. We present a patient of MuSK MG associated with multicentric Castelman disease.