Spindle Cell Lipoma With Florid Primary Follicular Lymphocytic Hyperplasia: A Novel Association With Potential Diagnostic Pitfalls

ABSTRACT

Spindle cell lipoma (SCL) is a benign subcutaneous lipomatous neoplasm with a heterogeneous histologic appearance that varies greatly depending on the amount of fat, collagen, and myxoid stroma, which define the multiple subtypes of SCL, such as fat poor SCL, pseudoangiomatous SCL, and dendritic fibromyxolipoma. Cutaneous lymphoid hyperplasia is a spectrum of benign conditions characterized by reactive B-cell and T-cell cutaneous lymphocytic infiltrates. Cutaneous B-cell lymphoid hyperplasia is a heterogeneous group of non-neoplastic conditions that can be observed as reactive phenomena to infections, medications, allergens, or neoplasms and must be distinguished from cutaneous B-cell lymphomas. Here, we report a novel case of spindle cell lipoma, associated with B-cell primary lymphoid follicular hyperplasia, mixed within the tumor in a peculiar pattern, while discussing potential diagnostic pitfalls with low-grade B-cell lymphomas. This is the first report of such association in the literature.

Graph-based description of tertiary lymphoid organs at single-cell level

Our aim is to complement observer-dependent approaches of immune cell evaluation in microscopy images with reproducible measures for spatial composition of lymphocytic infiltrates. Analyzing such patterns of inflammation is becoming increasingly important for therapeutic decisions, for example in transplantation medicine or cancer immunology. We developed a graph-based assessment of lymphocyte clustering in full whole slide images. Based on cell coordinates detected in the full image, a Delaunay triangulation and distance criteria are used to build neighborhood graphs. The composition of nodes and edges are used for classification, e.g. using a support vector machine. We describe the variability of these infiltrates on CD3/CD20 duplex staining in renal biopsies of long-term functioning allografts, in breast cancer cases, and in lung tissue of cystic fibrosis patients. The assessment includes automated cell detection, identification of regions of interest, and classification of lymphocytic clusters according to their degree of organization. We propose a neighborhood feature which considers the occurrence of edges with a certain type in the graph to distinguish between phenotypically different immune infiltrates. Our work addresses a medical need and provides a scalable framework that can be easily adjusted to the requirements of different research questions.

Histological Disorganization of Spleen Compartments and Severe Visceral Leishmaniasis

The spleen is a secondary lymphoid organ responsible for immune surveillance against blood-circulating pathogens. Absence of the spleen is associated with increased susceptibility to systemic spread and fatal infection by different pathogens. Severe forms of visceral leishmaniasis are associated with disorganization of spleen compartments where cell interactions essential for splenic immunological function take place. White pulp atrophies, secondary lymphoid follicles and marginal zones vanish, and the boundaries separating white and red pulp blur. Leukocyte populations are reduced or disappear or are replaced by plasma cells. In this paper, we review the published data on spleen disorganization in severe forms of visceral leishmaniasis and propose a histological classification to help the exchange of information among research groups.

Characteristics of the minor salivary gland infiltrates in Sjögren's syndrome

Sjögren's syndrome (SS) is a chronic autoimmune exocrinopathy associated with variable degree of lymphocytic infiltration of the affected organs (primarily salivary and lacrimal glands) and broad clinical manifestations. Minor salivary gland (MSG) lesions mainly consist of T and B cells, while antigen-presenting cells have been reported in heavy infiltrates. Evidence suggests that the infiltrate composition differs according to lesion severity; however, these differences are not well-defined. To investigate the differential distribution of the major infiltrating mononuclear cell (MNC) types in SS-lesions of variable severity, total-T, CD4(+)-T, CD8(+)-T, Treg, and B cell, macrophage (MPhi), interdigitating (iDC) and follicular dendritic cell (fDC), and natural-killer (NK)-cell incidence (%-total infiltrating MNC) was analyzed in MSG biopsies with mild (n = 11), intermediate (n = 13) or severe (n = 15) lesions. T cells, CD4(+)-T cells and Tregs, B lymphocytes, MPhis and iDCs were significantly different among MSG tissues with mild, intermediate or severe inflammatory lesions, while CD8(+)-T cell, fDC and NK cell incidence was not correlated with lesion severity. T cell, CD4(+)-T cell, T/B cell ratio and iDC incidence was negatively, whereas B cell and MPhi incidence was positively correlated with infiltration grade and biopsy focus score. Tregs predominated in intermediate lesions. Multivariate analysis revealed several associations between the incidence of each infiltrating MNC-type and disease manifestations, implying an involvement of local immune responses in systemic disease features. Our findings support that the distribution of infiltrating MNCs at the SS-lesions varies according to lesion severity and correlates with disease manifestations. The significance of this differential distribution and the underlying aetiopathogenic factors need to be elucidated.

Multiscale modeling of cell mechanics and tissue organization

Nowadays, experimental biology gathers a large number of molecular and genetic data to understand the processes in living systems. Many of these data are evaluated on the level of cells, resulting in a changed phenotype of cells. Tools are required to translate the information on the cellular scale to the whole tissue, where multiple interacting cell types are involved. Agent-based modeling allows the investigation of properties emerging from the collective behavior of individual units. A typical agent in biology is a single cell that transports information from the intracellular level to larger scales. Mainly, two scales are relevant: changes in the dynamics of the cell, e.g. surface properties, and secreted molecules that can have effects at a distance larger than the cell diameter.

On propagation of excitation waves in moving media: the FitzHugh-Nagumo model

Background

Existence of flows and convection is an essential and integral feature of many excitable media with wave propagation modes, such as blood coagulation or bioreactors.

Methods/Results

Here, propagation of two-dimensional waves is studied in parabolic channel flow of excitable medium of the FitzHugh-Nagumo type. Even if the stream velocity is hundreds of times higher that the wave velocity in motionless medium (), steady propagation of an excitation wave is eventually established. At high stream velocities, the wave does not span the channel from wall to wall, forming isolated excited regions, which we called “restrictons”. They are especially easy to observe when the model parameters are close to critical ones, at which waves disappear in still medium. In the subcritical region of parameters, a sufficiently fast stream can result in the survival of excitation moving, as a rule, in the form of “restrictons”. For downstream excitation waves, the axial portion of the channel is the most important one in determining their behavior. For upstream waves, the most important region of the channel is the near-wall boundary layers. The roles of transversal diffusion, and of approximate similarity with respect to stream velocity are discussed.

Conclusions

These findings clarify mechanisms of wave propagation and survival in flow.