Trabeculae Of Lymph Nodes Research Articles

Enzootic bovine leucosis in cows on farms in Almaty and Turkestan regions of Kazakhstan

The objective of this study was to evaluate pathomorphological and histopathological characteristics of internal organ tissues and skeletal muscles of Black-Motley cows with bovine laeukemia necropsied between 2013 and 2017. Pathomorphological and histopathological assessment of enzootic bovine leukosis was performed. The viral presence was proved by haematological study, enzyme-linked immunosorbent assay and agar-gel immunodiffusion. There was the pathomorphological manifestation of an immunosuppressive condition in the cattle, as well as leukemic cell accumulations in the brain, kidneys, duodenum, spleen, lymph nodes, cardiac and skeletal muscles. Our study is considered to bear significance concerning the description of microstructural changes involving lymph node trabeculae and myocardial fibres from leukemic cows. This investigation, therefore, provides new knowledge on histopathological features of enzootic bovine leucosis, which potentially may bring new insights into the disease mechanisms.

Nevus Cell Aggregates in Lymph Nodes

The article by Holt et al1 in this issue of the Journal looks again at the issue of nevus cell aggregates in lymph nodes and contributes substantially to our understanding of the phenomenon. At the same time, like all good studies, it raises some important questions that remain to be answered. In this editorial, I briefly summarize what is known about the frequency of nevus cells in lymph nodes, their locations in terms of gross and microscopic anatomy, the means used to identify them, and the prevailing theories of how nevus cells might get there in the first place. Finally, I briefly mention some of the practical diagnostic dilemmas that can arise when nevus cells are found in lymph nodes. The occurrence of nevus cell aggregates in lymph nodes has been known at least since Stewart and Copeland’s 1931 report, and subsequent studies indicate that it no longer can be considered a rare phenomenon.2 Among patients with melanoma undergoing lymph node biopsy or lymphadenectomy, 3% to 22% have had nodal nevi.3,4 In patients with melanoma, nodal nevi have been found in 0.12% to 0.54% of nodes from full lymph node dissections,3,5 1.2% of nodes from selective lymph node dissections,4 and 3.9% to 13% of sentinel lymph nodes.4,6 Their frequency is less in lymphadenectomy specimens for breast carcinoma, having been found in 0.33% of patients and in 0.017% to 0.1% of lymph nodes in this setting.3,4 Nevus cells also have been encountered in lymph nodes from patients with no known malignancy, as well as in regional nodes associated with adnexal carcinoma of the skin and squamous cell carcinoma of the tonsil.7 The greater frequency of nevus cell aggregates in sentinel nodes removed for melanoma, as opposed to nonsentinel nodes, has been demonstrated convincingly, although the search for melanocytes in these sentinel nodes tends to be more vigorous, often including multiple levels and immunohistochemical analysis. Nevus cells have been found most often in axillary lymph nodes, but they also have been identified in cervical and inguinal regions; involvement of visceral nodes is rare.4,8 In most cases, the cellular aggregates have the appearance of conventional nevus cells. However, node involvement also has been seen with blue nevus, cellular blue nevus, and plexiform spindle cell nevus, as well as atypical spitzoid tumors.3,9-12 The most common locations of nevus cell aggregates, by far, are the capsule or trabeculae of lymph nodes.3,4,6 Occasionally they can be observed adjacent to small vessels4,9 or within lymphatic vessels surrounding the nodes.13 The nevus cells are surrounded by a delicate reticulin meshwork, a finding not associated with melanoma cells.14 However, there have been a number of reports of nevus cells within cortical or medullary parenchyma or in marginal sinuses3,13,15; Biddle et al7 recently reported 13 such cases. When present in nodes, cellular blue nevi often are found in the peripheral sinuses or parenchyma,16,17 a finding that has led some to postulate a different mechanism from the usual capsular site of conventional nevus cell aggregates.3,18 Nevus cell aggregates most often are found on H&E-stained sections, but additional cases are identified with immunohistochemical analysis.19 The cells most often are positive for S-100 or MART-1, but they are negative or only weakly positive for HMB-45.4,7 In contrast with metastatic melanoma cells, nevus cell aggregates tend to be negative for the proliferation marker Ki-67.7,20 The theories of how nevus cells arrive in or around lymph nodes can be divided into 2 broad categories: (1) arrested migration of neural crest progenitor cells during

Intraparenchymal nevus cell aggregates in lymph nodes: a possible diagnostic pitfall with malignant melanoma and carcinoma.

It is well documented that nevus cells can be found within the fibrous capsule and trabeculae of lymph nodes; however, it is less well known that nevus cells can also be found in the lymph node parenchyma. We report the findings in 13 cases of nevus cell aggregates located within the cortical and/or medullary parenchyma of lymph nodes. Seven of the 13 patients had a primary diagnosis of melanoma, three had no known malignancy, one had breast carcinoma, one had adnexal carcinoma of the skin, and one had squamous cell carcinoma of the tonsil. Of the seven patients with melanoma, four had axillary lymph node dissections and three had inguinal lymph node dissections. The patient with adnexal carcinoma had metastatic carcinoma in 14 of 20 lymph nodes that had been dissected; one of them also had intraparenchymal nevus cells. The patient with squamous cell carcinoma of the tonsil had an intraparenchymal nevus cell aggregate in one of the 21 dissected lymph nodes; all 21 were negative for carcinoma. Nests of intraparenchymal nevus cells ranged from clusters of only a few cells up to 2.1-mm aggregates. No mitotic figures, prominent nucleoli, or lymphatic-vascular invasion were detected in any of the melanocytic aggregates. The melanocytic cells of the nevus cell aggregates expressed S-100 protein and/or MART-1 but not gp100 protein (HMB-45). Less than 1% of the nevus cells expressed Ki-67. The purpose of this study was to draw attention to the finding of nevus cells in the parenchyma of lymph nodes and to alert pathologists to this as a potential diagnostic pitfall, especially in patients with concurrent melanoma or carcinoma. Awareness that nevus cells can be present in nodal parenchyma, analysis of their morphologic features (including comparison with any previous or existing melanoma or carcinoma), and immunophenotyping will help pathologists to establish the correct diagnosis in most instances.

A large proportion of bovine T cells express the γδ T cell receptor and show a distinct tissue distribution and surface phenotype

The numbers, phenotype, and tissue distribution of gamma delta T cells in cattle were studied using two monoclonal antibodies (mAbs) which react with the bovine gamma delta T cell receptor (TCR). Both mAbs stained 20-40% of T cells in peripheral blood, and immunoprecipitated molecules of 44 and 36 kd (reduced) and 70-80 kd (non-reduced). In cattle the majority of circulating gamma delta T cells showed a distinct surface phenotype; they expressed T19, a 215 kd molecule described in sheep and cattle which marks only gamma delta T cells. Bovine gamma delta T cells were also CD2-, CD4-, and mostly CD8-, and failed to express CD6, a molecule possibly involved in T cell activation. The distribution of gamma delta T cells in cattle lymphoid tissues differed markedly from that in humans, in that bovine gamma delta T cells were concentrated around lymph node trabeculae and were usually sparse or absent from the B cell and T cell domains of lymph nodes. Like most other species studied, gamma delta T cells in cattle were localized to epithelial surfaces, particularly within the skin and intestine, indicating that it was at these sites where gamma delta T cells functioned. Our results provide further evidence for the unusual localization, recirculation pattern, and phenotype of gamma delta T cells, and also show that some features of gamma delta T cells can differ quite markedly from species to species.

Three distinct subpopulations of sheep T lymphocytes.

Monoclonal antibodies reactive with distinct T lymphocyte subpopulations have been described in man, mouse and rat and structural analyses of these antigens have demonstrated a high degree of evolutionary conservation. This report describes the reactivity of three monoclonal antibodies (mAb), 19-19, alpha SBU-T4 and alpha SBU-T8, which define T cell subpopulations in the sheep. The mAb alpha SBU-T4 and alpha SBU-T8 define the sheep CD4 and CD8 molecules, respectively. These two antigens show similar tissue distributions, molecular weights and fluorescence-activated cell sorter profiles to human, mouse and rat CD4 and CD8 molecules. The mAb 19-19 is reactive with a subpopulation of T lymphocytes which displays a tissue distribution unlike that reported for a T cell subset in any other species. 19-19 stains 7% of efferent lymph lymphocytes, 15% of peripheral blood lymphocytes but only 1-3% of lymph node lymphocytes. Two-color immunofluorescence demonstrates that the 19-19+ T cell subset is SBU-T4- and SBU-T8-, and thus defines a third T cell subpopulation in sheep. Immunohistology on frozen lymph node tissue sections localizes 19-19 mAb-reactive cells to the subcapsular region of the lymph node and lymph node trabeculae. Only 1% of thymocytes are 19-19+ and these cells are located mainly in the medulla and often arranged as foci around blood vessels. The 19-19 mAb immunoprecipitates from sheep lymphocytes an antigen with an apparent molecular mass of 215 kDa under both reducing and nonreducing conditions. It is concluded that alpha SBU-T4 and alpha SBU-T8 recognize the sheep homologues of the human T4 and T8 antigens, respectively, whereas 19-19 recognizes an antigen (termed SBU-T19) which has not been reported in any other species.

Nevus cell aggregates in submandibular lymph nodes

Nevus cell aggregates are occasionally found in the capsules and trabeculae of lymph nodes. These aggregates are similar histologically to those in typical cutaneous nevi and should be differentiated from metastatic tumor.

Smooth muscle in lymph node capsule and trabeculae.

This study focuses on the confusion in existing literature concerning the presence of smooth muscle in the capsule and trabeculae of lymph nodes. Human and bovine nodes from several anatomical areas and several individuals of each species were examined by conventional light, electron and fluorescence microscopy. Smooth muscle cells, independent of blood vessels, were demonstrated in the trabeculae and capsules of lymph nodes of both species examined by all three techniques. The need for further study on the function of these cells is indicated.