Cluster of Differentiation 54 (CD54), also known as intracellular adhesion molecule-1 (ICAM-1), is a transmembrane glycoprotein belonging to the immunoglobulin superfamily. Although CD54 has been shown to be involved in cell-to-cell adhesion and proliferation of B-cell lymphoma cell lines, the clinical significance of its expression has not yet been elucidated. We analyzed Ki-67 indices, the expression status of CD54 and its receptor (CD11a), and the intercellular distance of tumor cells in 40 diffuse large B-cell lymphoma (DLBCL) cases with vascular invasion to analyze the association of cell adhesion and proliferation status. CD54 and CD11a were simultaneously expressed (double-positive) in extra/intravascular tumor cells in 14 (35%) of the cases. Histologically, lymphoma cells of the double positive cases exhibited significantly higher Ki-67 index in extravascular tumor cells than that in the intravascular ones, while no difference was observed in lymphoma cells of the non-double positive cases. The significantly shorter extravascular intercellular distance compared with the intravascular intercellular distance suggested the association between cell-cell adhesion mediated by CD54 and cell proliferation. We further confirmed that the treatment of the recombinant LFA1 (CD11a/CD18) showed the adhesion of human DLBCL-derived cell line HBL-2 to LFA1 and increased cell viability. These findings suggest that cell-to-cell adhesion via CD54 maintains the cell proliferative activity of a subset of DLBCL. This study provides a valuable foundation upon which further research may be conducted to determine detailed mechanisms of cell-to-cell-associated and adhesion-independent cell proliferation.

Primary thyroid lymphoma is a rare type of cancer. Most cases involve large B-cell lymphomas (LBCLs), which largely show good prognoses. However, the reasons for this have not been understood. To identify the factors influencing the favorable clinical outcomes of thyroid LBCLs, clinicopathological and genetic analyses of 21 cases of thyroid LBCLs were performed, including immunohistochemistry, fluorescence in situ hybridization (FISH), and analysis for MYD88 mutations based on the World Health Organization Classification of Tumors, 5th Edition. The median age of the patients was 70 years (range, 54–80 years). Fifteen patients (71%) had limited-stage disease. The 5-year overall survival rate was 83% (95% confidence interval: 56%–94%). No instances of central nervous system (CNS) recurrence was observed. The series included 15 cases with diffuse LBCL not otherwise specified (DLBCLnos) and 6 cases with transformation of indolent BCLs (T-IBCLs). Immunohistochemistry subdivided DLBCLs into 12 germinal center B-cell (GCB) and 9 non-GCB subtypes. FISH analysis revealed split signals of MYC in 2/17 cases, MALT1 in 0/15 cases, and BCL6 in 3/15 cases. No MYD88 mutations were detected in any of the cases (0/21). The factors contributing to the favorable clinical course in thyroid LBCLs were a higher proportion of GCB phenotypes and the lack of MYD88 mutations in DLBCLnos and T-IBCLs. Even MYC-R cases showed better prognosis. Further studies involving a large series of LBCLs in extranodal organs are needed to expand on the findings of this study.

This study retrospectively evaluated the computed tomography (CT) findings of idiopathic multicentric Castleman disease (iMCD) at a single center and compared the CT findings of iMCD-TAFRO with those of iMCD-non-TAFRO. CT images obtained within 30 days before diagnostic confirmation were reviewed for 20 patients with iMCD (8 men and 12 women, mean age 52.8 ± 12.3 years, range 25–74 years). Twelve patients were diagnosed with iMCD-TAFRO, five with iMCD-idiopathic plasmacytic lymphadenopathy, and three with iMCD-not otherwise specified. CT images revealed anasarca and lymphadenopathy in all 20 patients. The iMCD-TAFRO group showed significantly higher frequencies of ascites (100% vs. 37.5%, P = 0.004), gallbladder wall edema (75.0% vs. 12.5%, P = 0.020), periportal collar (91.7% vs. 25.0%, P = 0.004), and anterior mediastinal lesions (non-mass-forming infiltrative lesions) (66.7% vs. 12.5%, P = 0.028). Para-aortic edema tended to be more frequent in patients with the iMCD-TAFRO group (83.3% vs. 37.5%, P = 0.062), while the absence of anterior mediastinal lesions tended to be more frequent in the iMCD-non-TAFRO group (16.7% vs. 62.5%, P = 0.062). These CT findings may have clinical implications for improving the accuracy and speed of iMCD diagnosis and differentiating iMCD-TAFRO from other subtypes.

Idiopathic multicentric Castleman disease (iMCD) is a type of Castleman disease unrelated to the Kaposi sarcoma-associated herpesvirus/human herpesvirus type 8 (KSHV/HHV8) infection. Presently, iMCD is classified into iMCD-IPL (idiopathic plasmacytic lymphadenopathy), iMCD-TAFRO (thrombocytopenia, anasarca, fever, reticulin fibrosis/renal insufficiency, and organomegaly), and iMCD-NOS (not otherwise specified). The most common treatment for iMCD is using IL-6 inhibitors; however, some patients resist IL-6 inhibitors, especially for iMCD-TAFRO/NOS. Nevertheless, since serum IL-6 levels are not significantly different between the iMCD-IPL and iMCD-TAFRO/NOS cases, cytokines other than IL-6 may be responsible for the differences in pathogenesis. Herein, we performed a transcriptome analysis of cytokine storm-related genes and examined the differences between iMCD-IPL and iMCD-TAFRO/NOS. The results demonstrated that counts per million of STAT2, IL1R1, IL1RAP, IL33, TAFAIP1, and VEGFA (P < 0.001); STAT3, JAK2, MAPK8, IL17RA, IL18, TAFAIP2, TAFAIP3, PDGFA, VEGFC, CXCL10, CCL4, and CXCL13 (P < 0.01); and STAT1, STAT6, JAK1, MAPK1, MAPK3, MAPK6, MAPK7, MAPK9, MAPK10, MAPK11, MAPK12, MAPK14, NFKB1, NFKBIA, NFKBIB, NFKBIZ, MTOR, IL10RB, IL12RB2, IL18BP, TAFAIP6, TNFAIP8L1, TNFAIP8L3, CSF2RBP1, PDGFB, PDGFC, and CXCL9 (P < 0.05) were significantly increased in iMCD-TAFRO/NOS. Particularly, upregulated IL33 expression was demonstrated for the first time in iMCD-TAFRO/NOS. Thus, inflammatory signaling, such as JAK-STAT and MAPK, may be enhanced in iMCD-TAFRO/NOS and may be a cytokine storm.

A 72-year-old male patient presented fatigue, anemia, elevated total protein, IgG, IgG4, IL-6, and vascular endothelial growth factor (VEGF) levels. Initial diagnostics suspected multiple myeloma. A plane computed tomography (CT) scan showed pneumonia and the enlargement of generalized lymph nodes. A lymph node biopsy revealed a mix of immature and mature plasma cells, significant IgG4-positive cells, and IL-6-secreting plasma cells, mimicking plasmacytoma, IgG4-related disease, and Castleman disease, ultimately leading to a diagnosis of hyper IL-6 syndrome. Treatment with antibiotics improved the patient’s condition without the need for additional therapies, including tocilizumab.

Reactivation of hepatitis viruses during chemotherapy can be problematic in the treatment of malignant lymphomas. However, studies on reactivation of chronic hepatitis C virus (HCV) infection are limited. A 43-year-old woman presented with generalized lymphadenopathy and multiple liver tumors, and she was diagnosed with follicular lymphoma (grade 3a; clinical stage IV). Chronic HCV infection was clinically diagnosed. Immunochemotherapy (ICT), including bendamustine and obinutuzumab, was initiated with close liver function monitoring without specific treatment for hepatitis C. However, liver dysfunction worsened 17 days after ICT initiation, and ICT was interrupted. HCV-RNA and transaminase levels continued to elevate. Liver biopsy results confirmed acute exacerbation of chronic hepatitis C. Direct active antiviral (DAA) therapy was started and effective. She has maintained a sustained virologic response since DAA therapy ended. With regard to lymphoma, complete metabolic response was maintained for 4 years without additional treatment. Physicians should be aware of HCV reactivation with hepatitis flare after ICT for lymphoma and consider the indication and timing of DAA therapy for hepatitis C in this setting.

A 79-year-old Japanese woman presented with exertional dyspnea. She had cardiac tamponade and urgent pericardial drainage was performed. Pathological findings from the pericardial fluid revealed non-germinal center B-cell (non-GCB) pericardial large B-cell lymphoma (CD10^-, BCL6⁺, and MUM1⁺). Although a diagnosis of fluid overload-associated large B-cell lymphoma was considered, GCB nodal diffuse large B-cell lymphoma (CD10⁺, BCL6⁺, and MUM1⁺) was discovered through needle biopsy of the enlarged left axillary lymph node. Despite the two lymphomas exhibiting different expression levels of CD10, polymerase chain reaction assessing IgH gene rearrangement suggested a clonal relationship between them. Additionally, MYD88 L265P mutation was confirmed using Sanger sequencing in both samples, suggesting the MCD type. Our case highlights a discrepancy between the Hans’ criteria and the gene expression profile-based cell of origin.

Juvenile xanthogranuloma (JXG) is a rare benign non-Langerhans cell histiocytosis that usually occurs in cutaneous lesions on the head, neck, or upper trunk of neonates and young children. Intramuscular JXG, which invades muscle tissue, accounts for only 0.6% of all JXGs and mostly occurs in the skeletal muscles of the extremities or trunk. A 5-month-old girl was referred to our hospital. At the age of 3 months, she presented with a slow-growing lump on her left thigh. Magnetic resonance imaging (MRI) showed a 22 × 19 × 18 mm oval mass in her left thigh. First, needle biopsy results suggested deep JXG or myeloid sarcoma. Therefore, marginal resection was performed. Intraoperatively, the tumor adhered to the left tensor fasciae latae muscle and was resected together. Histopathological examination revealed a diffuse monotonous sheet-like proliferation of mononuclear histiocyte-like cells with pale, eosinophilic, foamy cytoplasm with a background of muscle and fatty tissue. Minimal mitotic figures and no nuclear atypia or multinucleated giant cells were observed. Immunohistochemical analysis was positive for CD68 (KP-1) and CD163; weakly positive for lysozyme; and negative for CD1a, S100, myeloperoxidase, and CD34. No blast proliferation was observed in the bone marrow. The patient was diagnosed with deep JXG and scheduled for periodic physical examination and MRI. Despite positive margins, the patient fared well without local recurrence 48 months after tumor removal. Understanding the unique pathology of deep JXG and detailed histological evaluation are important for decision-making.

Intravascular accumulation of atypical large lymphoid cells is a rare condition that necessitates a differential diagnosis of intravascular lymphoma (IVL). Recently, a non-neoplastic condition known as benign atypical intravascular CD30+ T-cell proliferation (BAITP) has been identified. This condition is characterized by CD30+ and CD3+ or CD4+ atypical T-cells and is often associated with trauma and chronic inflammation. This case highlights atypical intravascular lymphoid cells of the uterine cervix that are positive for CD30 and CD56 and can mimic IVL.