Polycomb group (PcG) proteins are important for the regulation of hematopoiesis by regulating chromatin compaction and silencing genes related to differentiation and cell cycle. Overexpression of enhancer of zeste homologue 2 (Ezh2) and Bmi-1/PCGF4 has been implicated in solid organ cancers, while Mel-18/PCGF2 has been reported as a tumor suppressor. Detailed expression profiles of PcG proteins and their diagnostic significance in malignant lymphomas are still unknown. In this study, we analyzed the expression levels of Ezh2, Bmi-1, Mel-18, and Ki67 in 197 Hodgkin's and non-Hodgkin's lymphoma patient samples and in lymphoma cell lines using immunohistochemistry, fluorescent immunocytochemistry, and Western blotting. Immunohistochemical staining showed that Ezh2 expression was significantly increased in aggressive compared to indolent subtypes of B cell neoplasms (P = 0.000-0.030), while no significant differences in Bmi-1 expression were found between these subtypes. Compared to the normal counterpart, T cell lymphomas showed significant overexpression of Bmi-1 (P = 0.011) and Ezh2 (P = 0.000). The Ki67 labeling index showed a positive correlation with Ezh2 expression in B cell lymphomas (correlation coefficient (Co) = 0.983, P = 0.000) and T/NK cell lymphomas (Co = 0.629, P = 0.000). Fluorescent immunohistochemical staining showed coexpression of Ezh2 and Ki67 in the same tumor cells, indicating that Ezh2 expression correlates with cell proliferation. Both B and T/NK cell neoplasms showed low expression of Mel-18 and high expression of both Bmi-1 and Ezh2. In conclusion, in aggressive lymphoma variants, Ezh2 is strongly expressed and polycomb repressive complex PRC1.4 dominates over PRC1.2. Coexpression of Bmi-1 and Ezh2 is a characteristic of aggressive lymphomas. Ezh2 correlates with the proliferation and aggressive nature of non-Hodgkin's lymphomas.

Plasma cell-type Castleman disease (PCD) is often encountered when differentiating IgG4-related disease (IgG4-RD). Given that serum IgA is often elevated in Castleman disease, we investigated whether IgA expression levels in histological specimens can be used to differentiate between the two diseases. Lymph node lesions obtained from 12 IgG4-RD and 11 PCD patients were analysed by immunohistochemistry with anti-IgG, -IgG4, and -IgA antibodies. In addition to all 12 cases of IgG4-RD, 8/11 cases (72.7 %) of PCD also met the diagnostic criteria of IgG4-RD (serum IgG4 ≥135 mg/dl and IgG4/IgG-positive cells ≥40 %). IgA-positive cells were sparsely and densely distributed in IgG4-RD and PCD cases, respectively. The median number of IgA-positive cells ± SD in all 12 cases of IgG4-RD was 31 ± 37 cells per three high-powered fields (3HPFs) (range 4-118 cells/3HPFs). In contrast, the median number of IgA-positive cells, which was significantly higher in all 11 cases of PCD, was 303 ± 238 cells/3HPFs (range 74-737 cells/3HPFs) (P < 0.001). In conclusion, our findings indicate that in cases where serum analysis-based data are unavailable, anti-IgA immunostaining can be used for differential diagnosis of IgG4-RD.

Immunoglobulin (Ig) G4-related disease has been recently described. This disease affects various organs, including lymph nodes. We describe the case of a 52-year-old Japanese man with IgG4-related lymphadenopathy with inflammatory pseudotumor (IPT)-like features. Five years ago, the patient noticed a painless mass in the mandible but did not consult a doctor. Recently, he noted that the mass had increased in size and consulted an oral surgeon in the hospital. Excisional biopsy was performed for diagnosis. Histopathological examination revealed that most of the enlarged lymph node was occupied by the hyalinized tissue. A few residual lymphoid follicles with hyperplastic germinal centers and infiltration of plasma cells and eosinophils were observed. Most of the plasma cells expressed IgG4, and the ratio of IgG4-positive cells to IgG-positive cells was 57.1%. These findings were consistent with IgG4-related lymphadenopathy. In conclusion, pathologists should consider IgG4-related lymphadenopathy when diagnosing a lesion with IPT-like features.

Two autopsy cases of cystic brain lesion in utero are reported. One of them was a donor infant of twin transfusion syndrome. The baby died immediately after birth and showed multicystic encephalomalacia in the distribution of the anterior cerebral artery. The second baby was a stillborn infant with thanatophoric dwarfism with associated chronic periventrlcular leukomalacia (PVL). It was suggested that the multicystic encephalomalacia and chronic PVL found in the first and second cases were caused by persistent circulatory disturbances in utero.

Background Awareness of pre-travel consultations (PTCs) and prevention methods for overseas travel-related diseases, and the understanding of PTCs among Japanese travelers and medical professionals remains low in Japan. A multicenter registry was established to examine PTCs in Japan. This study assessed the PTC implementation rate and examined the indicators of PTCs that can be used as criteria for evaluating quality. Methods Clients who presented for their PTCs at 17 facilities and were registered between February 1, 2018, and May 31, 2020, were included. Medical information was extracted retrospectively via a web-based system. Correlations between vaccination risk categories and advice/intervention proportions by the facility were evaluated using Spearman’s ordered phase relations (α = 0.05). Results Of the 9700 eligible clients (median age, 32 years; 880 [9.1%] aged < 16 years and 549 [5.7%] aged ≥65 years), the most common travel duration was ≥181 days (35.8%); higher among younger clients. The most common reason for travel was business (40.5%); the US (1118 [11.5%]) and Asia (4008 [41.3%]) were the most common destinations and continents, respectively. The vaccine number (median three per person) increased after the PTCs except for the tetanus toxoid. Only 60.8% of the clients recommended for malaria prophylaxis received anti-malarial agents. The gross national income; the incidence of human rabies, typhoid fever, falciparum malaria; and dengue risk category were associated with the percentage of hepatitis-A vaccines; explaining rabies post-exposure prophylaxis, typhoid-fever vaccinations, malaria-prophylaxis prescriptions; and mosquito repellants, respectively. Conclusions Although the characteristics of the travelers differed, the quality of the PTCs should be improved to address, for example, the lower rate of acceptance of malaria prophylaxis in Japan.