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Biomedical subjects

K W Min

Publications and source records attributed to K W Min.

123 records · Page 7Linked to original sources
PubMedDate not supplied

Small intestinal stromal tumors with skeinoid fibers in neurofibromatosis: report of four cases with ultrastructural study of skeinoid fibers from paraffin blocks.

Small intestinal stromal tumors (SIST) with skeinoid fibers (SF) are reported in four patients with neurofibromatosis. SF appeared as intercellular eosinophilic globules that stained positively on periodic acid-Schiff stain and bluish on Masson trichrome stain, like those reported previously. Electron microscopic confirmation of SF was carried out on tissue retrieved from paraffin blocks, which revealed diagnostic ultrastructural features of SF. The association of SIST with SF and neurofibromatosis enhances the diagnostic value of SF as a marker of neurogenic spindle cell tumors. This study also underscores the importance of electron microscopy for differentiation of SF from pseudoskeinoid structures, which may mimic SF on light microscopic examination.

Adult↗
PubMedDate not supplied

Pineal parenchymal tumors: an ultrastructural study with prognostic implications.

The pineal gland is host to a spectrum of neoplasms. Those considered to be derived from or differentiating toward pineal parenchymal cells are rare. Traditionally, pineal parenchymal tumors (PPTs) have been divided into 3 types: pineocytomas, pineoblastomas, and mixed or transitional tumors. Their characterization has been far from adequate and no firm diagnostic criteria, light microscopic or ultrastructural, have been established. In an attempt to provide more precise prognostic diagnostic criteria, we undertook a detailed ultrastructural analysis of 17 PPTs and found them to exhibit light microscopic and ultrastructural features strikingly similar to those of pineal parenchymal cells in varying stages of development, ranging from undifferentiated primitive neuroepithelial cells to mature pineal parenchymal cells. We endorse classification of PPTs based on a combination of their light microscopic and ultrastructural features. Accordingly, PPTs can be divided into three categories: 1) pinealoblastoma, 2) PPTs of intermediate or mixed differentiation, and 3) pineocytoma, a tumor of mature-appearing pineocytes. In keeping with this classification, our 3 pinealoblastomas behaved as highly malignant tumors. A correlation of morphology and prognosis was less evident between intermediate tumors and pineocytomas, perhaps the result of considerable variation in surgical and other therapies. Evidence of neurosensory differentiation, a feature noted to a varying extent in all but the pineoblastomas, included club-shaped "nerve endings" in 7 tumors, small numbers of dense core granules in 8, clear vesicles in 7, and structures suggestive of synapses in 4. With the exception of 3 undifferentiated PPTs or pinealoblastomas lacking nerve endings, all pineocytomas exhibited some combination of these markers of neuronal specialization. In that the ultrastructural features of these PPTs were more indicative of their aggressiveness than was their degree of light microscopic differentiation or grade, we consider electron microscopy a useful adjunct, not only in diagnosis but also in therapeutic decision-making and prognostication.

Adolescent↗
PubMedDate not supplied

Peculiar membranogranular glomerular deposits.

Two patients with immune complex diseases, one with IgA nephropathy and the other with systemic lupus erythematosus, were found to have peculiar membranogranular deposits in the glomeruli in addition to typical immune complex deposits. There was no clinical indication of familial lipodosis in either case. The deposits were very similar to those seen in lecithin-cholesterol acyltransferase-deficient patients. The pathogenetic role of lipid deposits in the glomerulus is discussed.

Adult↗
PubMedDate not supplied

Usefulness of electron microscopy in the diagnosis of "small" round cell tumors of the sinonasal region.

The sinonasal region is known to harbor several types of tumors that belong to the general category of "small" round cell tumors and offer considerable diagnostic challenges. This study evaluated 33 cases of such tumors by electron microscopy to characterize their ultrastructural features in conjunction with immunohistochemistry, in an attempt to define diagnostic criteria of various types. Electron microscopy was useful in the proper classification of tumors in 27 cases: esthesioneuroblastoma (EN), 12; undifferentiated carcinoma, 6; melanoma, 3; lymphoma, 3; melanotic neuroectodermal tumor, 1; rhabdomyosarcoma, 1; and pituitary adenoma, 1. In the remaining six cases, the ultrastructural features were those of poorly differentiated carcinomas. They usually exhibited some epithelial characteristics as well as neuroendocrine features by immunohistochemistry and electron microscopy. These tumors could be best described as poorly differentiated neuro-endocrine carcinomas (malignant neuroepitheliomas). The most controversial diagnostic problems existed between the tumors categorized as esthesioneuroblastomas and neuroendocrine (NE) carcinomas. Esthesioneuroblastomas were characterized by uniform round nucleated cells with variable amounts of dendritic processes containing numerous dense core granules ranging from 150 to 350 nm in the perikarya and dendritic processes. Dendritic processes contained longitudinally arranged neural tubules and revealed an occasional synaptic junction. In three of the 12 cases of EN, cells with the appearance of sustentacular cells were recognized by electron microscopy. The NE carcinomas usually consisted of closely packed round cells with scanty cytoplasm that lacked any feature of neuroblastic cells. The tumor cells in this category often were epithelioid in appearance and exhibited a varying degree of cytokeratin positivity. Neuron-specific enolase was also positive in all cases, further suggesting their neuroepithelial nature. The greatest difference between EN and NE carcinomas was the absence of sustentacular cells in NE carcinomas. Immunohistochemical and electron microscopic studies are essential in the differential diagnosis of EN and NE carcinomas, because their microscopic appearance is very similar. The study indicates that EM is useful in the diagnostic categorization of sinonasal tumors of uncertain nature, particularly when it is used in conjunction with immunohistochemistry.

Carcinoma↗
PubMedDate not supplied

Multinucleated giant stromal tumor of the omentum: report of a case with immunohistochemical and ultrastructural investigation.

Multinucleated giant stromal cells (MGSC) have been described in a variety of lesions of various anatomical sites. They are generally believed to be derived from fibroblasts or myofibroblasts. Their size and bizarre appearance may lead to an erroneous interpretation of infiltrating malignant cells, but they are regarded as reactive in nature. MGSC also seem to participate in a neoplastic process and form a part of tumors called giant cell fibroblastomas (GCF). In GCF, multinucleated giant cells are sparsely scattered throughout the tumor, which is composed of loosely arranged spindle cells. Thus far, no tumor composed of MGSC entirely, to the best of the authors' knowledge, has been reported. This study involved an 80-year-old female with an omental tumor, which is believed to represent the first case of tumor of MGSC. The patient developed abdominal pain; a large abdominal tumor measuring 18 x 15 x 5 cm by computerized tomography was found located between the left lobe of the liver, the transverse colon, and the greater curvature of the stomach. Although the tumor was adherent to the above organs and infiltrating the omentum, it was resectable. Grossly, the tumor was highly vascular and the surface was shaggy with no recognizable capsule. The cut surfaces were red to tan with frequent cystic spaces containing bloody material. Microscopically, the tumor cells were large and multinucleated (2-6 nuclei) with prominent nucleoli. The cytoplasm was abundant and stained amphophilic. These tumor cells formed moderately cellular sheets filling the spaces between the varying sized vessels. There was prominent vascularity throughout the tumor. DNA study by image analysis revealed aneuploidy peaks. On immunohistochemistry, the tumor cells were strongly positive for vimentin, moderately positive for actin along the periphery of the cytoplasm, and negative for cytokeratin, EMA, myoglobin, S-100, CEA, Factor XIIIa, HMB-45, and HAM56 and KP-1. Ultrastructurally, the cytoplasm contained rich profiles of RER with scattered lysosomes. The cell borders were slightly irregular with occasional subplasmalemmal densities facing loosely arranged collagenous stroma. The light microscopic, immunohistochemical, and electron microscopic features of tumor cells were remarkably similar to MGSC. The tumor size and gross appearance suggested a malignancy, but it was a diploid tumor and the patient remains disease free 5 years after a complete resection.

Aged↗
PubMedDate not supplied

Skeinoid fibers in mesectodermal leiomyoma of the ciliary body.

Unlike smooth muscle elsewhere in the body, the smooth muscle of the iris and ciliary body is derived from neuroectoderm (mesectoderm). Leiomyomas that arise from the ciliary body, and therefore are of mesectodermal origin, may resemble spindle cell neurogenic tumors by light microscopy. They show positive immunostaining for smooth muscle actin but negative staining for neural markers. Ultrastructurally, the cells have the features of smooth muscle cells. The authors report a typical case of mesectodermal leiomyoma in a 47-year-old woman in which skeinoid fibers, considered to be an ultrastructural marker of neurogenic spindle cell tumors, were frequent together with other ultrastructural features often seen in neuroglial cell tumors. The findings indicate that mesectodermal leiomyoma is unique in its histogenesis as well as in its morphology.

Biomarkers↗
PubMedDate not supplied

Gangliocytic paraganglioma of the duodenum: report of a case with immunocytochemical and ultrastructural investigation.

A case of gangliocytic paraganglioma is reported in a 70-year-old female presenting as a polypoid tumor of the second portion of the duodenum. Immunohistochemical and ultrastructural features of the tumor indicate that gangliocytic paraganglioma of the duodenum (GPD) represents an unique tumor originating from the neuroectodermal derivative exhibiting dual phenotypic expression toward paraganglionic and epithelial (neuroendocrine) cells. These findings correlate well with the literature and it is further suggested that GPD belongs to the histopathologic spectrum of tumors derived from the neural crest. The findings offer a plausible explanation for histogenetic possibilities of the occurrence of pure epithelial tumors (i.e., carcinoid-like tumors) in the paraganglionic systems. The patient remains with no evidence of disease 4 years following a simple polypectomy.

Aged↗
PubMedDate not supplied

Diagnostic usefulness of sustentacular cells in paragangliomas: immunocytochemical and ultrastructural investigation.

Neuroendocrine tumors may derive either from neuroectoderm or endoderm. Both may present with a similar histologic pattern known as "Zellballen" regardless of their histogenetic origin, making it difficult to separate the two different histogenetic entities in certain cases. To evaluate the usefulness of sustentacular cells in the recognition of tumors of paraganglionic origin, the authors analyzed immunohistochemical and ultrastructural characteristics of 25 paragangliomas and 19 pulmonary and 10 small intestinal carcinoids. Sustentacular cells with characteristic dendritic features, strong immunoreactivity for S-100 protein, and agranular cytoplasm by electron microscopy were found consistently in the paragangliomas and not found in typical carcinoid tumors, except for four examples of spindle cell carcinoid of the lung. The presence of sustentacular cells in tumors with "Zellballen" pattern therefore denotes paraganglionic origin.

Adrenal Gland Neoplasms↗
PubMedDate not supplied

Fructose precipitates calcium phosphate in the kidneys of female rats fed magnesium-deficient diets.

We have previously shown the synergistic interaction between fructose and magnesium (Mg) deficiency on renal calcification of female rats. The purpose of the present study was to determine whether the calcification formed in the kidneys of female rats fed an Mg-deficient fructose diet is due to phosphate or oxalate precipitates of calcium. The rats were divided into two dietary groups: fructose without Mg and starch with Mg. Rats were fed their respective diets for 9 weeks, and 24 h urine was collected for measuring urinary output, pH, Mg and calcium (Ca). The rats were then fasted overnight and after decapitation, blood was immediately collected for measuring plasma Ca and Mg, and the kidneys were removed. Left kidneys were used to determine their Mg and Ca contents, and right kidneys were dissected and fixed in neutral buffered formalin. Formalin-fixed specimens for microscopy were processed in paraffin using conventional procedures. Histochemical analysis was conducted by staining serial paraffin sections with haematoxylin, eosin, PAS-Schiff, alcian blue and trichrome. The sections were stained by the von Kossa method for calcium phosphate and by the silver hydroperoxide method for calcium oxalate. Only calcium phosphate was detected in the corticomedullary junction of the kidneys of female rats fed Mg-deficient fructose. The hypercalcaemia, hypercalciuria, and hypomagnesuria observed in the fructose group may cause calcium phosphate crystallization. A possible mechanism for the interaction between magnesium deficiency, fructose and oestrogen may be through parathyroid hormone which increases tubular fluid Ca and phosphorus (TF[Ca]x[P]). Further studies are required to prove the mechanism proposed here.

Animals↗
PubMedDate not supplied

Comparison of renal calcium concentration in obese, lean, diabetic, and non-diabetic Zucker rats fed a magnesium-deficient fructose diet.

In order to determine the effects of hypoinsulinaemia or hyperinsulinaemia on nephrocalcinosis induced by the interaction between fructose and magnesium (Mg) deficiency, we compared kidney calcification in obese versus lean, and non-diabetic versus diabetic female Zucker rats fed a magnesium-deficient fructose diet. One half of the obese and lean animals, respectively, was injected with streptozotocin to produce diabetes, and the other half was injected with citrate buffer alone. Diabetic, non-diabetic, obese, and lean animals were divided into two dietary groups, consisting of high starch or high fructose without added Mg. After a four week period, 24 hour urine was collected for urinary output, protein, oxalate, citrate, MG, and calcium (Ca) measurements. The animals were then decapitated, and blood was collected for glucose, Mg, and Ca determinations, and kidneys were removed to determine their Mg and Ca contents. All fructose-fed animals exhibited significantly more kidney Ca then the starch-fed animals. Lean non-diabetic rats fed fructose showed the greatest kidney Ca along with the greatest urinary protein excretion among all experimental groups. The significant finding in the present study is that diabetes or obesity reduced nephrocalcinosis regardless of the insulin status of the rats. Diuresis and hypercitraturia in diabetic and/or obese animals may cause a reduction in nephrocalcinosis induced by the interaction between fructose and magnesium deficiency. Hyperproteinuria (uromucoid) in combination with hypercalciuria and hypomagnesuria may be responsible for greater nephrocalcinosis in the fructose than the starch group. The possible mechanisms for this interaction on nephrocalcinosis have been discussed.

Animals↗
PubMedDate not supplied

Perineurial cell ensheathement of muscle fibers: a new syndrome of fatigable muscle weakness mimicking myasthenia gravis.

Many newly discovered pathological and physiological variants of neuromuscular junction function have been identified. We report a case of a myasthenia gravis-like syndrome with onset of ptosis at age six years and eventual evaluation for peripheral weakness twenty years later. Subsequent muscle biopsy showed a previously unreported finding of perineurial cell ensheathement of the muscle fibers. We suggest that the ensheathement of the muscle cells by perineurial cells may alter the microenvironment interfering with neuromuscular transmission.

Adult↗
PubMedDate not supplied

Adrenal cortical nodule mimicking small round cell malignancy on fine needle aspiration.

The cases of two elderly female patients with benign adrenal cortical nodules that mimicked small round cell malignancies by fine needle aspiration cytology are reported. Electron microscopic examination of part of the aspirate revealed the cells to be aggregates of bare nuclei of broken adrenal cortical cells, leading to a correct diagnosis.

Adrenal Cortex↗
PubMedDate not supplied

Bridging circulatory support before heart transplant without invasion of the mediastinum.

Heart transplantation is becoming a useful tool in the clinical treatment of patients with end-stage cardiac decompensation. Donor organs are not always available at a critical time for a patient waiting for a transplant. Bridging techniques have been described that use mechanical support systems. This article describes the use of femoral-venous to femoral-arterial bypass over a period of 50 hours in a 38-year-old woman waiting for a donor heart. Because the patient sustained cardiopulmonary arrest before organ availability, mechanical circulatory support that used femoral-venous to femoral-arterial bypass was instituted. The patient's own lungs were used as an oxygenator. Pump flow levels were determined by the level of central aortic oxygen saturation. Successful transplant was performed, and bridging, therefore, was done without invasion of the mediastinum.

Adult↗