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Biomedical subjects

N Masawa

Publications and source records attributed to N Masawa.

At least 19 recordsLinked to original sources
PubMed2005

Mesenteric arterionecrosis in natural and experimental equine endotoxaemia.

To test the hypothesis that mesenteric arterionecrosis (MA) occurs in horses with naturally occurring endotoxaemia (ET) and in those with experimentally induced ET, the mesentery and gastrointestinal tract of 21 Thoroughbred racehorses (15 with spontaneous colic suspected to be due to ET, and six with experimentally induced ET) were examined. MA, which occurred in 13 of the 15 horses with spontaneous colic and in all six of the cases of experimental ET, was morphologically similar in the two groups of animals. This suggested that the pathogenesis of the MA was fundamentally similar in the two groups, and that MA is a pathognomonic feature of equine ET. In addition to histolysis of the arterial walls associated with infiltration of blood components, changes were noted in the medial smooth muscle including formation of many intracellular vacuoles within single smooth muscle cells, cytoplasmolysis, necrosis with granules and vacuoles, and coagulation necrosis; similar changes have been observed in cases of prolonged angiospasm or vasoconstriction. It is suggested that the effects of sustained arterial contraction leading to intimal and medial damage influence the pathomorphogenesis of MA.

Animals↗
PubMed2005

Floral variant of follicular lymphoma containing marginal zone B-cell component. Report of two cases.

We here report two unusual cases of floral variant of follicular lymphoma containing marginal zone B-cells. Histologically, the neoplastic follicles consisted of three distinct layers. The inner layer was composed of neoplastic germinal centers exhibiting a floral design and the middle layer had unusually prominent mantle zones. The outer zone of neoplastic follicles was surrounded by a pale cuff of marginal zone B-cells. Immunohistological study demonstrated that both the germinal center and marginal zone component lay within the follicular dendritic cell network. The germinal center component was CD10+ and bcl-2+. However, a portion of the marginal zone component weakly expressed bcl-2 but not CD10. Nodal marginal zone B-cell lymphoma (NMZBL) occasionally possesses "floral" lymphoid follicles. Follicular lymphoma with marginal zone differentiation is a high-risk variant of follicular lymphoma. In diagnostic practice, the differential diagnosis between the floral variant of follicular lymphoma containing marginal zone B-cells and the "floral variant" of NMZBL is important.

Adult↗
PubMed2001

The pathogenesis of cerebrovascular lesions in hypertensive rats.

In this study we investigated the pathogenesis of hypertensive cerebrovascular lesions by light microscopy, immunohistochemistry, scanning electron microscopy, and transmission electron microscopy. The brains of rats with experimentally induced hypertension exhibited severe edema and intracerebral hemorrhage. Light microscopy of the arteries showed severe medial lesions and the deposition of fibrinoid substance in the intima. Immunohistochemistry showed that intercellular adhesion molecule (ICAM)-1, platelet-endothelial cell adhesion molecule (PECAM)-1, interleukin (IL)-1alpha, IL-6, IL-8, and tumor necrosis factor (TNF)-alpha endothelial cell expression was upregulated. Scanning electron microscopy of these arteries revealed the adhesion of neutrophils, monocytes, and a few platelets to endothelial cells, and their invasion of endothelial cell junctions and opened junctions. Transmission electron microscopy showed neutrophil and monocyte adhesion to the endothelial cells and neutrophil and monocyte invasion of endothelial cell junctions, intimal deposition of fibrinoid substance, and severe medial cell injury. Intravenously injected horseradish peroxidase insulated from endothelial cell junctions and, via pinocytotic vesicles, into the subendothelial space. These findings suggest that hypertension activates endothelial cells to increase the expression of adhesion molecules and cytokines, and induces neutrophil and monocyte adhesion and migration, resulting in endothelial cell injury and increased permeability of endothelial cells, which results in hypertensive arterial disease.

Animals↗
PubMed2001

Acute viral lymphadenitis mimicking low-grade peripheral T-cell lymphoma. A clinicopathological study of nine cases.

Acute viral lymphadenitis, especially infectious mononucleosis (IM), often shows the presence of Reed-Sternberg-like cells, resulting in confusion with Hodgkin's disease. However, acute viral lymphadenitis requiring differential diagnosis from non-Hodgkin's lymphoma is not widely recognized. We describe the clinicopathological and immunohistochemical features of lymph node lesions from nine such patients which pose serious problems of differential diagnosis from low-grade peripheral T-cell lymphoma. There were three males and six females with ages ranging from 21 to 44 years (median 25 years). All patients had "B" symptoms and multicentric lymphadenopathy. The clinical course was also self-limiting. Each lymph node specimen showed an obvious expansion of an interfollicular area by pleomorphic and polymorphous infiltration with an increased number of arborizing postcapillary venules. The infiltrate was composed of variable numbers of small and medium-sized lymphocytes, immunoblasts, plasma cells in various stage of maturation and occasional granulocytes. The small lymphocytes usually had regular round nuclei, whereas the medium-sized lymphocytes occasionally showed nuclear pleomorphism. Hyperreactivity of B-lymphocytes, including hyperplastic germinal centers and/or foci of monocytoid B-cells, was seen in parts of the lesion. The majority of the interfollicular T-lymphocytes, including T-immunoblasts, expressed CD8 antigen. Various numbers of TIA-1-positive small and medium-sized T-cells were observed in the paracortical area. Despite these findings, the overall histological picture of this series posed serious difficulties when differentially diagnosing this condition from low-grade peripheral T-cell lymphomas such as angioimmunoblastic T-cell (AILD) and T-zone types, indicating that viral lymphadenitis occasionally presents with histological features of AILD and T-zone lymphomas. To avoid overdiagnosis and overtreatment, we emphasize the need to pay careful attention to the clinical and laboratory findings as well as the morphological features.

Acute Disease↗
PubMed2001

Lymph node necrosis in systemic lupus erythematosus. A histopathological and immunohistochemical study of four cases.

The lymph node lesions of lupus lymphadenitis are characterized by necrosis sometimes accompanied by hematoxylin bodies, but only a few immunohistological analyses of this unique lesion have been reported. In this study we investigated the immunopathogenesis of these lesions. Lymph node specimens from four patients were analyzed immunohistochemically by applying recently developed monoclonal antibodies to immunocompetent cells. Necrosis occupied almost the entire lymph node in two cases (extensive type), whereas small foci of necrosis were found in the paracortex in the remaining two (localized type). No hematoxylin body formation was detected in any of the samples. Necrosis of the small muscular arteries, arterioles and venules was seen in the necrotic areas in all four cases. In one case of the localized type, necrotizing angitis was seen in a few arterioles and venules in the non-necrotic area. By immunohistology, amorphous depositions of immunoglobulins and C3 were demonstrated in the walls of the arterioles and venules in two cases. Our findings indicate that vasculitis due to local deposition of immune complexes in the blood vessels may play an important role in the pathogenesis of necrosis in lupus lymphadenitis.

Adult↗
PubMed2001

Angioimmunoblastic T-cell lymphoma with hyperplastic germinal centers: a clinicopathological and immunohistochemical study of 10 cases.

An absence of germinal centers is one of the histological characteristics of angioimmunoblastic T-cell lymphoma (AITL). We report here 10 unusual cases of AITL with hyperplastic germinal centers. The clinical presentation of each patient was characterized by generalized lymphadenopathy, constitutional symptoms and polyclonal hypergammaglobulinemia. The initial biopsy findings of each patient were similar and were characterized by hyperplastic germinal centers with ill-defined borders and a proliferation of high endothelial venules (HEV). In the paracortical area there was a mixed infiltrate including irregularly shaped clusters or small nests of clear cells in all cases. Moreover, the clear cells invaded the lymphoid follicles, resulting in expansion of the germinal centers, except for one case. Immunohistochemistry revealed that the tumor cells, including clear cells, were CD4-expressing T cells. Some of the atypical lymphocytes were also Bcl-6-positive. A majority of the follicular dendritic cell networks showed a normal/reactive or an expanded/disrupted pattern in all cases. Moreover, three lesions possessed a few large irregularly shaped proliferations of follicular dendritic cells around the HEV Four cases progressed to AITL within a few years. The present 10 cases probably represent an early stage of AITL preceding follicular dendritic cell hyperplasia. Detection of clear cells, Bcl-6-positive atypical T lymphocytes, and foci of irregularly shaped proliferation of follicular dendritic cells appears to be critical for early diagnosis and treatment of AITL with hyperplastic follicles.

Aged↗
PubMed2001

Different roles of arteriosclerosis in the rupture of intracranial dissecting aneurysms.

AIMS: Although intracranial dissecting aneurysm (IDA) is a newly described variant of the brain aneurysms that affects mainly the vertebrobasilar arterial system, its pathogenesis remains obscure. We aimed to clarify the role of arteriosclerosis in the pathogenesis of IDA based on histopathological findings in seven autopsy cases of IDA. METHODS AND RESULTS: All cases exhibited systemic hypertension or left ventricular hypertrophy. Macroscopically, all cases exhibited subarachnoid haemorrhage. Two types of dissection were recognized in the vertebral artery. Six of seven IDA cases showed a widespread disruption of the entire thickness of the arterial wall with the formation of a dilated pseudoaneurysm, which consisted of thin adventitia (arterial wall disruption type). Medial disruption of the arterial wall and subadventitial dissecting haemorrhage were also found, resulting in the formation of a false lumen and stenosis of the 'true' lumen of the artery. However, these lesions were connected to the site of rupture of the entire arterial wall. Within 1 day after onset of IDA, the autopsy cases showed formation of fibrin thrombus, marked leucocyte infiltration and necrosis of the arterial wall at the site of the lesion. Cases that survived more than 1 week showed smooth muscle cell proliferation, macrophage accumulation and lymphocytic infiltration in the lesions. These cases showed no atherosclerotic plaque, but non-atherosclerotic fibrocellular intima. The thickness of intima and media was significantly less in the vertebral artery of IDA patients than that of non-IDA patients with systemic hypertension. On the other hand, the remaining case showed severe atherosclerosis with haemorrhage into the lipid core without connection to the arterial lumen (intra-atheromatous plaque haemorrhage type). However, unusual arterioles and neovascularization of the intra-and peri-arterial walls were observed. CONCLUSIONS: Our results suggest that disruption of the entire arterial wall may be a critical event in the development of IDA and result in the medial disruption and subadventitial haemorrhage. Non-atheromatous intima might function as a protective factor in arterial wall disruption. On the other hand, atherosclerosis may predispose to intra-atheromatous plaque haemorrhage type of IDA through intramural haemorrhage originating from the newly formed vessels.

Adult↗
PubMed2001

Autoimmune disease-associated lymphadenopathy with histological appearance of T-zone dysplasia with hyperplastic follicles. A clinicopathological analysis of nine cases.

Autoimmune disease-associated lymphadenopathy shows marked histopathological and clinical diversity. We describe the clinicopathological and immunohistochemical findings of nine cases of autoimmune disease-associated lymphadenopathy, which posed a serious differential diagnostic problem regarding T-zone dysplasia with hyperplastic follicles. There were two males and seven females aged 25 to 65 years (median 37 years). The patients had multicentric lymphadenopathy in association with clinical and laboratory findings suggestive of an "autoimmune disease". Four patients were diagnosed to have systemic lupus erythematosus (SLE), and the remaining five patients had antiphospholipid antibody syndrome and Sjogren's syndrome (SS), rheumatoid arthritis (RA), chronic thyroiditis, RA and SS, and SLE and SS, respectively. None of the nine patients developed malignant lymphomas during the follow-up periods from 44 to 225 months (median 103 months). The lesions were characterized by paracortical hyperplasia with prominent vascular proliferation and many lymphoid follicles with germinal centers. The paracortical area usually contained numerous small T-lymphocytes without cytological atypia, accompanied by a variable number of plasma cells, B-immunoblasts, and histiocytes. Polymerase chain reaction analysis demonstrated no clonal rearrangement of the T-cell receptor chain gene in four cases examined, although immunoglobulin heavy chain rearrangement was detected in only one case. These findings suggest that autoimmune disease-associated lymphadenopathy, especially SLE, shares the histological features with T-zone dysplasia with hyperplastic follicles. The nine cases presented here should be differentiated from T-zone lymphoma with follicles and angioimmunoblastic lymphoma with hyperplastic germinal centers. To avoid overdiagnosis and overtreatment, we emphasize the need to turn attention to these clinical and laboratory findings as well as to the morphological features.

Adult↗
PubMed2001

Marginal zone B cell lymphomas of Waldeyer's ring--a report of two tonsillectomy cases resembling histomorphological features of inflammatory lesions.

We identified two cases of lymphoma of the mucosa-associated lymphoid tissue (MALT) type in 11 tonsillectomy specimens of primary B cell lymphoma of Waldeyer's ring. Both patients were Japanese females presenting with bilateral enlargement of the palatine tonsils. One had a history of chronic otitis media. In that case, the lesion was characterized by an extrafollicular growth pattern with marginal zone-like arrangement. The tumor was mainly composed of medium-sized cells with round or indented nuclei with scant cytoplasm (centrocyte-like cells). In the other patient, most tumor cells were mature plasma cells, plasmacytoid cells, proplasmacytes, and immunoblasts with scattered centrocyte-like cells. Tropism of tumor cells for the epithelium was noted in both lesions. Primary marginal zone B cell lymphoma of the MALT type arising from Waldeyer's ring has rarely been reported in the literature, causing certain diagnostic problems. Various florid reactive lymphoproliferative disorders, including chronic tonsillitis and infectious mononucleosis, should be differentiated from this type of primary Waldeyer's ring lymphoma.

Adult↗
PubMed2001

Inflammatory pseudotumor of lymph nodes: clinicopathologic and immunohistological study of 11 Japanese cases.

We report 11 Japanese cases of inflammatory pseudotumor (IPT) of the lymph node. There were 7 males and 4 females with ages ranging from 5 to 68 years (median; 48). Only 2 patients had systemic lymphadenopathy, and all others had involvement of only 1 lymph node group. Constitutional symptoms such as fever were present in 8 patients and laboratory abnormalities were detected in 5. All patients recovered and were alive and well after 2 to 180 months (median; 32 months). Histologically, the process mainly involved the connective tissue framework of the lymph node, secondarily spreading into the lymph node parenchyma and the perinodal tissue. It was characterized by a storiform growth pattern of myofibroblasts, marked vascularity with associated vascular lesions, and a polymorphous reactive cellular infiltrate in a collagen-rich stroma. An immunohistochemical study revealed numerous myofibroblasts, histiocytes, and vascular endothelial cells expressing vascular endothelial growth factor (VEGF) in 6 cases. It was suggested that VEGF may be involved, in part, in the induction of the angiogenesis of IPT. Moreover, the present study indicates that follicular dendritic cell sarcoma, nasal T/natural killer cell lymphoma, and anaplastic large cell lymphoma should be added to the differential diagnosis from IPT of the lymph node. Int J Surg Pathol 9(3):207-214, 2001

Adolescent↗
PubMed2001

Follicular lymphoma of the salivary gland: a clinicopathological and molecular study of six cases.

To clarify the clinicopathologic, immunohistologic, and genotypic features of follicular lymphoma arising from the salivary glands, we examined 20 cases of operatively resected primary salivary gland lymphoma and identified 6 such cases. There were 4 women and 2 men with ages ranging from 38 to 64 years (median 50 years). The tumor arose from the parotid gland in 4 cases and the submandibular gland in the remaining 2. Four patients were stage IE and 2 were stage IIE-1. The median follow-up period was 49 months and all patients were alive and well at the time of going to press. Histologically, 5 patients were follicular lymphoma grade 2, and 1 was grade 3. In all specimens in noninfiltrating salivary gland tissue, there was periductal lymphocytic infiltration near the lymphoma. Moreover, myoepithelial sialoadenitis was noted in 2 lesions. An immunohistochemical study revealed all 6 cases were CD10+, CD79a+, bcl-6+, CD3-, CD5-, CD21-, CD23-, and CyclinD1-. The tumor cells expressed bcl-2 in 3 cases and p53 oncoprotein in 4 cases. Two cases revealed clonal bands with polymerase chain reaction (PCR) assay for the immunoglobulin heavy (IgH) gene. The bcl-2/IgH translocation at the major breakpoint region was detected in 1 case (16%). We found a relatively high incidence of follicular lymphomas (30%) in salivary gland lymphomas. Among the mucosa-associated lymphoid tissue (MALT) system, follicular lymphomas appeared to occur frequently in the salivary glands as well as the duodenum and skin. Moreover, follicular lymphoma arising from the salivary glands appeared to have some of the characteristics of MALT-type lymphoma including indolent prognosis, presence of myoepithelial sialoadenitis, and rarity of the BCL-2 gene rearrangement.

Adult↗
PubMed2001

Inflammatory pseudotumor of the submandibular gland: report of a case presenting with autoimmune disease-like clinical manifestations.

We report a rare case of inflammatory pseudotumor arising in the submandibular gland, which presented with autoimmune disease-like clinical manifestations. A 70-year-old Japanese man developed masses in both submandibular regions. Laboratory tests revealed polyclonal hypergammaglobulinemia, high titers of antinuclear antibody, and a positive thyroid test. Histologically, the lesion was composed of multiple nodules separated by thick fibrous bands and contained a few atrophic lymphoid follicles and residual ductal structures. At higher magnification, the nodules contained numerous mature plasma cells mixed with myofibroblasts, lymphocytes, and histiocytes. Occasionally, the myofibroblasts were arranged in poorly formed fascicles and in a storiform pattern. Polymerase chain reaction analysis failed to demonstrated the rearrangement of the immunoglobulin heavy-chain gene. The patient was free of disease after 72 months follow-up. Marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (MALT) type arising from salivary glands occasionally showed prominent plasma cell differentiation. The present case indicates that inflammatory pseudotumor should be added to the list of different diagnoses for mucosa-associated lymphoid tissue-type lymphoma of the salivary glands.

Aged↗
PubMed2000

Pathology of a dissecting intracranial aneurysm.

The pathological findings of six autopsy cases of dissecting intracranial aneurysm are studied. Clinically, all cases exhibited systemic hypertension or left ventricular hypertrophy. Macroscopically, all cases exhibited rupture of the vertebral artery and subarachnoid hemorrhage. Two types of lesion were present. First, all cases showed the formation of a dilatated pseudoaneurysm with widespread disruption of the entire arterial wall, which was composed of thin adventitia. Second, a medial disruption of the arterial wall and subadventitial dissecting hemorrhage, which formed a false lumen and stenosis of the 'true' lumen of the artery, was also found. However, these lesions were found to be connected to the site of rupture. The autopsy cases within 1 day of onset of intracranial dissecting aneurysm showed the formation of fibrin thrombus, a marked degree of leukocyte infiltration and necrosis of the arterial wall at the site of the lesion. The cases that survived more than 1 week showed smooth muscle cell proliferation, macrophage accumulation and lymphocytic infiltration. No arteriosclerosis was found in any lesion studied. These data suggest that the disruption of the entire arterial wall might initially occur and cause medial disruption and subadventitial hemorrhage. Hypertension and arteriosclerosis might function as causal and protective factors in the pathogenesis of dissecting intracranial aneurysms, respectively.

Adult↗
PubMed2000

Reactive follicular hyperplasia in the lymph node lesions from systemic lupus erythematosus patients: a clinicopathological and immunohistological study of 21 cases.

To clarify the clinicopathological and immunohistological findings of reactive follicular hyperplasia in systemic lupus erythematosus (SLE) lymphadenopathy, we examined 21 such cases, including four males and 17 females. Three main patterns could be delineated: pattern A, histological features of Castleman's disease (n = 6); pattern B, follicular hyperplasia with pronounced arborizing vasculature in the paracortex resembling T-zone dysplasia with hyperplastic follicles (n = 6); and pattern C, follicular hyperplasia without any other specific findings (n = 9). The patients who showed patterns A and B on histology were all female with a median age of 36 years, and presented with the lymphadenopathy within 4 months, some before a definitive diagnosis could be made. The group with pattern C included four males and five females with an age ranging from 20 to 58 years (mean, 37 years). In seven of them, the lymphadenopathy was noted 6 months or more after the therapy had been initiated. In a virological study, a small to moderate number of the lymphoid cells were positive for the Epstein-Barr virus-encoded small RNA in five of 10 cases examined. Human herpesvius 8 was not detected in the four cases examined by polymerase chain reaction and immunohistochemistry. The present study demonstrated that SLE lymphadenopathy showed histological variety and occasionally represented histopathological findings of multicentric Castleman's disease or findings similar to T-zone dysplasia with hyperplastic follicles in the biopsied specimens. We emphasize that careful attention to these morphological features, together with clinical and laboratory examinations, should allow a firm diagnosis of SLE to be made, providing information that is pertinent to the treatment of the disease. Moreover, disarray of the follicular dendritic cell (FDC) network, which could be easily detected by immunohistochemistry, was found in approximately 60% of our series. SLE lymphadenopathy should be listed as one of the diseases occasionally associated with disarray of the FDC network, although its clinicopathological significance remains unclear.

Adult↗
PubMed1999

Mast cell sarcoma with tissue eosinophilia arising in the ascending colon.

Mast cell sarcoma is a rare disease. We report an unusual case of this neoplasm arising in the ascending colon of a 32-year-old Japanese woman who presented with abdominal pain. An ulcerating mass in the colon was resected, along with enlarged mesenteric lymph nodes. Two years after surgery, the neoplasm recurred as left cervical lymphadenopathy and an intra-abdominal mass. Despite predonine and radiation therapy, the disease progressed, and the patient died. The tumor cells had abundant fine granular or clear cytoplasm, and oval, lobulated, or indented nuclei. Numerous mature eosinophils were intermingled with the tumor cells. Immunohistologic studies on paraffin sections demonstrated that the majority of the tumor cells were strongly positive for CD45RB, CD68, and mast cell tryptase. They were unreactive, however, with a broad spectrum of antibodies against myelomonocytic and lymphocytic antigens. The mast cell nature of this rare type of tumor can be best identifiable by immunostains for mast cell tryptase.

Adult↗
PubMed1998

Missense mutation (C1263R) in the thyroglobulin gene causes congenital goiter with mild hypothyroidism by impaired intracellular transport.

Metabolic abnormalities in thyroid hormonogenesis cause congenital goiter. Here we studied a case of mild hypothyroidism caused by a novel missense mutation in the thyroglobulin (TG) gene. A female patient underwent thyroidectomy twice at the age of 27 and 43 years because of gradual enlargement of the thyroid. By RNase cleavage assay and PCR direct sequencing we identified a thymine to cytosine transition at nucleotide 3828 (from the transcription start site) which causes amino acid change from cysteine to arginine at codon 1263. A pedigree study suggested autosomal recessive inheritance due to consanguineous marriage of her parents. Immunohistochemical study suggested impaired intracellular transport of the mutant TG. Sensitivity to endoglycosidase H confirmed that the mutant TG failed to reach the Golgi compartment. Native polyacrylamide gel electrophoresis and Western blot analyses showed that formation of monomers and homodimers was defective with abundant high molecular-weight aggregates which are normally formed transiently after translation. To examine if the mutant TG is functionally defective, we separated thyroid tissue extract on a Biogel A5m column and measured T4 and T3 released from proteins in each fraction by treatment with proteinase K. Although thyroid hormones released per mole of the mutant TG protein did not decrease, those released per mg of total protein decreased. In conclusion, the missense mutation in the TG gene caused congenital goiter with mild hypothyroidism due to an altered protein structure which resulted in defective intracellular processing and premature degradation by "quality control" mechanisms. Although the tissue TG content was greatly reduced, the hypothyroidism was mild with slow progression of the goiter, because the mutant TG was a relatively good substrate for the synthesis of the thyroid hormones.

Adult↗
PubMed1997

Ewing's sarcoma of the thumb.

The case of a 51-year-old man with Ewing's sarcoma of the thumb is presented. The tumor involved the distal phalanx of the right thumb, associated with an impressive extraskeletal mass. Histology revealed a round cell sarcoma with a positive immunoreactivity with monoclonal antibody O13. Five years after disarticulation at the metacarpophalangeal joint, the patient is alive without recurrence or metastasis.

Bone Neoplasms↗