No abstract

SummaryErythroblastic islands are anatomical units consisting of a central macrophage surrounded by erythroblasts. We studied the adhesion molecules involved in the formation of these structures. Central macrophages of erythroblastic islands isolated from the spleens of phlebotomized mice were dearly stained for vascular cell adhesion molecule 1 (VCAM-1). The surrounding erythroblasts of the erythroblastic islands strongly expressed the a4 integrin of very late activation antigen 4 (VLA-4:a4B1 integrin), the counter receptor of VCAM-1, whereas most reticulocytes and erythrocytes did not. Both monoclonal antibodies (mAbs) against oe4 integrin and VCAM-1 disrupted the erythroblastic islands cultured in the presence of erythropoietin. Moreover, adhesion of splenic erythroblasts to tumor necrosis factor a-stimulated mouse splenic endothelial cells, which showed high expression of VCAM-1 but not intercellular adhesion molecule 1, was inhibited by the anti-VCAM-1 and anti-a4 mAbs. These findings suggest that VLA-4-VCAM-1 interaction plays a crucial role in the formation of erythroblastic islands. Bone marrow resident macrophages (MCFs) establish stroma by extending long cytoplasmic processes and attaching to developing erythroid and myeloid cells (1, 2). These cells are both phenotypica[ly and functionally different from peritoneal M4's and monocytes (3, 4). In long-term bone marrow culture by which hematopoietic stem cells are maintained, immature myelomonocytic cells are attached to and proliferate on the M~s defined by the mAb F4/80 (5). The addition of erythropoietin to these cultures alternatively induces erythropoietic activity on the M~s, which form erythroblastic islands (EI) composed of central M~s and surrounding erythroblasts (Ebs) (6, 7). These lines of evidence suggest that erythropoietin-responsive erythroid precursors adhere to the M~s, where they are induced to proliferate and differentiate into erythrocytes by maintaining contact with the central M~s. To gain insight to the possible function of the M~s in erythropoiesis, we have considered it a priority to identify specific adhesion molecules involved in El formation (8).Recently, Morris et al. (9) characterized the nature of the adhesion using El isolated from fetal liver and found that the adhesion required divalent cations. Soligo et al. (10) demonstrated that a divalent cation-dependent adhesion molecule, very late activation antigen 4 (VLA-4) (a4B1) integrin, was present on Ebs, and that this molecule was localized at sites of intercellular contact between Ebs and M~s in human marrow, suggesting that VLA-4 might be involved in the adhesive interaction. The ligand of VLA-4 for cell-cell interaction is vascular cell adhesion molecule I (VCAM-1), which was first identified on TNF-ce-stimulated human umbilical endothelial cells (11,12). Using the bone marrow stromal cell culture system, VCAM-1 has been shown to be constitutively expressed in stromal cells, and to be involved in B lymphocyte-stromal cell (13) and hematopoietic stem cell-stromal cell i...

Despite high expectations for lung tumoroids, they have not been applied in the clinic due to the difficulty of their long-term culture. Here, however, using AO (airway organoid) media developed by the Clevers laboratory, we succeeded in generating 3 lung tumoroid lines for long-term culture (>13 months) from 41 lung cancer cases (primary or metastatic). Use of nutlin-3a was key to selecting lung tumoroids that harbor mutant p53 in order to eliminate normal lung epithelial organoids. Next-generation sequencing (NGS) analysis indicated that each lung tumoroid carried BRAFG469A, TPM3-ROS1 or EGFRL858R/RB1E737*, respectively. Targeted therapies using small molecule drugs (trametinib/erlotinib for BRAFG469A, crizotinib/entrectinib for TPM3-ROS1 and ABT-263/YM-155 for EGFRL858R/RB1E737*) significantly suppressed the growth of each lung tumoroid line. AO media was superior to 3 different media developed by other laboratories. Our experience indicates that long-term lung tumoroid culture is feasible, allowing us to identify NGS-based therapeutic targets and determine the responsiveness to corresponding small molecule drugs.

These cases were typical of secretory breast carcinoma, and were clinically, histologically and immunohistochemically analogous to acinic cell carcinoma of the salivary gland. We emphasize that secretory breast carcinoma and acinic cell carcinoma of the salivary gland may be identical lesions.

The distribution and pathological significance of sphingosine-1-phosphate receptor 1 expression are still unclear. In this study, we evaluated sphingosine-1-phosphate receptor 1's suitability as a diagnostic marker for malignant lymphoma by immunostaining formalin-fixed paraffin-embedded sections using a well-defined commercial anti-sphingosine-1-phosphate receptor 1 antibody. Sphingosine-1-phosphate receptor 1 was strongly expressed on the surface of small lymphocytes forming primary lymphoid follicles and in the mantle zone of secondary lymphoid follicles. Microarray-based immunohistochemistry with tissue samples from 85 lymphoid malignancy cases demonstrated that sphingosine-1-phosphate receptor 1 was expressed on the surface of mantle cell lymphoma cells. Strong expression was observed in all classical mantle cell lymphoma cases involving the lymph node (19 out of 19), gastrointestinal tract (10 out of 10), bone marrow (9 out of 9), and orbita (1 out of 1). Good results were obtained even in sections where cyclin D1 signals were lost because of over-fixation and/or decalcification. One aggressive variant of mantle cell lymphoma displayed a weaker membranous staining than classical mantle cell lymphoma in the lymph node and bone marrow. In a cyclin D1-negative mantle cell lymphoma of the orbita, no conclusive result was obtained. No cases of follicular lymphoma, marginal zone lymphoma, B lymphoblastic leukemia/lymphoma, or Burkitt's lymphoma showed any significant expression, whereas 2 out of 6 chronic lymphocytic leukemia/small lymphocytic lymphomas in bone marrow, 1 out of 3 lymphoplasmacytic lymphomas in the lymph node, and 2 out of 37 diffuse large B-cell lymphomas exhibited staining. A quantitative reverse transcription polymerase chain reaction-based analysis of mantle cell lymphoma lines revealed the sphingosine-1-phosphate receptor 1 mRNA expression level to be well correlated with the results of immunocytochemistry, flow cytometry, and western blotting. Thus, sphingosine-1-phosphate receptor 1 immunohistochemistry may be useful in the histological diagnosis of mantle cell lymphoma with formalin-fixed and paraffin-embedded sections. The antigen may be particularly valuable in cases where cyclin D1 immunostaining is not successful.

Autoimmune gastritis (AIG) is a special type of chronic gastritis characterized by autoimmune disorders caused by cellular immunity, resulting in the destruction of parietal cells and production of antiparietal cell antibodies. Endoscopic findings of AIG are mainly characterized by corpus‐dominant advanced atrophy. The antral area is generally considered to have no or mild atrophy; however, there are cases wherein the gastric mucosa is red or faded due to past infection with Helicobacter pylori or bile reflux. Currently, there are no diagnostic criteria for AIG in Japan, and it is important to make a diagnosis based on the presence of gastric autoantibodies and characteristic endoscopic and histological findings. AIG is associated with gastric cancer, neuroendocrine tumors (NETs), and other autoimmune diseases, such as thyroid diseases, anemia, and neurological symptoms due to impaired absorption of iron and vitamin B12, and thus requires systemic treatment. The significance of diagnosing AIG is to include patients as a high‐risk group for the development of gastric cancer and gastric NETs, provide an opportunity to detect autoimmune endocrine diseases, and initiate therapeutic intervention before anemia and neurological symptoms develop. It is important to pay close attention to the occurrence of AIG comorbidities not only at the time of AIG diagnosis but also during follow‐up after detection.

A case of solid-pseudopapillary carcinoma (SPC) of the pancreas in a 34-year-old Japanese woman is presented. An abdominal ultrasonography revealed a mass, which measured 10 cm in diameter, in the body and tail of the pancreas. The tumor was resected and it was originally diagnosed as a non-functioning islet cell tumor. One year and five months later, the patient was re-admitted to hospital, and liver metastasis was confirmed by ultrasonography. The patient died 6 days after the second transcatheter arterial embolization (TAE) required for the metastasis. The autopsy showed small foci of liver metastasis. A retrospective examination of the tumor suggested the diagnosis of SPC because of its characteristic solid and pseudopapillary structures, immunohistochemical findings, and liver metastasis. This case suggests that capsular invasion, specifically found at the surgical margin of the peritoneal side, may be an important pathological finding that is suggestive of malignant potential in solid-pseudopapillary tumor. If there is such a finding in a surgical specimen, an intensive follow up should be advised to the clinician.

We report here the first case of amebic meningoencephalitis caused by Balamuthia mandrillaris in a 78-year-old Japanese woman with Sjögren's syndrome. Fourteen days before her death, she presented with high fever and lost consciousness and later developed neck stiffness and abducens palsy. Computed tomography scans of the brain demonstrated multiple low-density areas throughout the brain. Neuropathologically, hemorrhagic and necrotic lesions with many amebic trophozoites were scattered in the brain and spinal cord. Granulomatous lesions were only rarely found. The amebas were identified as Balamuthia mandrillaris based on immunofluorescence assay. Clinicopathologically, our case was thought to be an intermediate between primary amebic meningoencephalitis due to Negleria fowleri and granulomatous amebic encephalitis due to Acanthameba species. Essentially, the case was one of an elderly person with suspected immunodeficiency with fulminant necrotic meningoencephalitis and scanty granulomatous lesions of 14 days course.