[Diagnosis and differential diagnosis of large B-cell lymphoma with IRF4 rearrangement].

Objective: To analyze the clinicopathological features and differential diagnosis of large B-cell lymphoma with IRF4 rearrangement, aiming enhance its recognition and prevent misdiagnosis. Methods: The clinicopathological features, immunophenotype, and fluorescence in situ hybridization (FISH) results of six cases diagnosed with IRF4 rearrangement-positive B-cell lymphoma at the Affiliated Hospital of Xuzhou Medical University from 2015 to 2023 were retrospectively analyzed. Additionally, a comprehensive review of the literature was conducted. Results: Six patients with IRF4 rearrangement-positive large B-cell lymphoma were included. Patients 1 to 5 included three males and two females with a median age of 19 years ranging from 11 to 34 years. Four patients presented with head and neck lesions, while the other one had a breast nodule; all were in clinical Ann Arbor stages I to Ⅱ. Morphologically, entirely diffuse pattern was present in two cases, purely follicular pattern in one case, and diffuse and follicular patterns in other two cases. The tumor cells, predominantly centroblasts mixed with some irregular centrocytes, were of medium to large size, with a starry sky appearance observed in two cases. Immunophenotyping revealed all cases were positive for bcl-6 and MUM1, with a Ki-67 index ranging from 70% to 90%, and CD10 was positive in two cases. IRF4 rearrangement was confirmed in all cases by FISH analysis, with dual IRF4/bcl-6 rearrangements identified in two cases, leading to a diagnosis of LBCL-IRF4. Case 6, a 39-year-old female with a tonsillar mass and classified as clinical Ann Arbor stage Ⅳ, displayed predominantly diffuse large B-cell lymphoma (DLBCL) morphology with 20% high-grade follicular lymphoma characteristics. Immunohistochemistry showed negative CD10 and positive bcl-6/MUM1, with a Ki-67 index of approximately 80%. Triple rearrangements of IRF4/bcl-2/bcl-6 were identified by FISH, leading to a diagnosis of DLBCL with 20% follicular lymphoma (FL). All six patients achieved complete remission after treatment, with no progression or relapse during a follow-up period of 31-100 months. Conclusions: Large B-cell lymphoma with IRF4 rearrangement is a rare entity with pathological features that overlap with those of FL and DLBCL. While IRF4 rearrangement is necessary for diagnosing LBCL-IRF4, it is not specific and requires differentiation from other aggressive B-cell lymphomas with IRF4 rearrangement.

[Expression of MSI1 and HER2 in mammary Paget's disease and their correlation with clinicopathological features and prognosis].

Objective: To investigate the expression of MSI1 and HER2 in mammary Paget's disease, and the correlation between the expression levels of MSI1 and HER2 and the clinicopathologic characteristics and prognosis of the patients. Methods: Clinical data and paraffin-embedded specimens of 34 pairs of mammary Paget's disease and underlying breast cancer were collected at the Department of Pathology, Affiliated Lianyungang Oriental Hospital of Xuzhou Medical University from March 2011 to December 2019. Immunohistochemistry was used to detect the expression of MSI1 and HER2 in mammary Paget's disease and the accompanying breast cancer, and to analyze the correlation between the expression levels of MSI1 and HER2 and their clinicopathologic features, as well as their influence on prognosis. Results: In mammary Paget's disease, the positive rate of MSI1 was 91.2% (31/34) and the positive rate of HER2 was 88.2% (30/34); the expression of MSI1 and HER2 was positively correlated (P=0.001, r=0.530). The expression of MSI1 was positively correlated with menopausal status (r=0.372, P=0.030) and lymph node metastasis (r=0.450, P=0.008). HER2 expression was positively correlated with menopausal status (r=0.436, P=0.010), and negatively correlated with ER expression (r=-0.365, P=0.034). The co-expression of MSI1 and HER2 was positively correlated with age (r=0.347, P=0.044) and menopausal status (r=0.496, P=0.003), and negatively correlated with ER expression (r=-0.461, P=0.006). Conclusions: MSI1 and HER2 are highly expressed in mammary Paget's disease and their expression levels are positively correlated. The correlation analysis between clinicopathological features and prognosis suggests that both of them may be involved in the occurrence and development of mammary Paget's disease and are potential therapeutic targets for mammary Paget's disease.

[ALK-positive large B-cell lymphoma with EBV infection or cyclin D1 expression: a clinicopathological analysis of 3 cases].

Objective: To investigate the clinicopathological features and misdiagnosis factors of ALK positive large B-cell lymphoma (ALK+LBCL). Methods: The clinicopathological data of 3 patients with ALK+LBCL in the Department of Pathology, the Affiliated Hospital of Xuzhou Medical University from 2010 to 2021 were collected retrospectively. Immunohistochemistry (IHC) was used for immunophenotyping, in-situ hybridization (ISH) for EBV-encoded RNA (EBER) detection, in-situ fluorescence hybridization (FISH, break-apart probes) for ALK, MYC, and CCND1 translocations. Next-generation sequencing (NGS) was used for the detection of gene fusions and mutations. And clinicopathological features and prognosis of patients were analyzed. Results: Among the 3 ALK+LBCL patients, there were 2 males and 1 female, aged 42, 59, and 39 years, respectively, none of which presented with B symptoms. Case 1 showed systemic lymphadenopathy with elevated serum EBV DNA loading, while cases 2 and 3 presented with extranodal lesions in the nasal and hard palate, respectively. Bone marrow biopsies were performed in cases 1 and 3, and neither showed involvement. Case 1 was at clinical stage Ⅲ while both cases 2 and 3 were at stage Ⅰ, and IPI score ranged 0-1 in all cases. The morphology of these cases was similar. The architecture was effaced by sheets of cohesive large cells growing in extensive infiltration and intra-sinus growth pattern. The neoplastic cells showed immunoblastic or plasmablastic morphology, and large anaplastic cells were easily found. The tumor cells expressed ALK protein cytoplasmically in almost all cells, with ALK gene translocations detected by FISH. Common B-cell and T-cell markers, including CD20, PAX5, CD19, CD2, CD3, CD5, CD7, CD43, CD56, and bcl-2, were negative, while plasmacytic differentiation markers, including CD138, CD38, and MUM1, were positive; CD22, BOB1 and OCT2 were variably expressed. CD10 was strongly expressed only in case 3. All cases were negative for bcl-6 but positive for CD4, perforin, CD30 (partial cells), pSTAT3 (diffusely), and MYC (40%-50%). The Ki-67 index was ranged 60%-70%. MYC translocation was not detected in any case by FISH. In case 1, EBER was strongly positive in>90% of tumor cells. Case 3 was diffusely positive for cyclin D1 but negative for SOX11 expression and CCND1 translocation. All cases harbored ALK fusion genes detected by NGS. In case 1, the fusion partner was TFG, which had not been reported in DLBCL, while in the other 2 cases, ALK fused with the CTCL gene, which was commonly seen in ALK+LBCL. Cases 1 and 3 were treated with ECHOP-based chemotherapy for six cycles and were followed up for 70 and 27 months, respectively, and both achieved complete remission. Conclusions: ALK+LBCL cases with diffuse EBER-positivity reported in this study show TGF as a new fusion partner of ALK in DLBCL, together with cyclin D1 expression. These rare cases are easily confused with EBV positive diffuse large B-cell lymphoma, not otherwise specified (EBV+DLBCL, NOS), cyclin D1 positive diffuse large B-cell lymphoma (cyclin D1+DLBCL) and ALK positive anaplastic large cell lymphoma (ALK+ALCL), resulting in misdiagnosis. Being aware of these rare phenotypes is essential for pathologists to diagnose ALK+LBCL and guide appropriate treatment accurately.