A malignant glycogen-rich adenocarcinoma of palatal salivary glands is reported. Histopathology revealed nonencapsulated nests and cords of polyhedral cells showing voluminous clear cytoplasms a n d cellular pleomorphisms, separated by fine vascular septae. Small and large ducts were infrequently seen showing apparent transition of large ducts into clear cells. The tumor cells were PAS-and Best-carmine positive, diastase soluble, and mucicarmine and Alcian-blue negative. Ultrastructurally , the tumor cells were arranged in solid nests and cords of electron-lucent cells surrounding single or multiple lumina, and surrounded by basement lamina. Occasional fusiform electron-dense cell processes were present beneath the basement lamina. The electron-lucent cells were joined by junctional complexes, contained in-tracytoplasmic canals, and were filled with massive accumulations of 0 glycogen particles. The electron-dense processes contained interlacing whorls of fine filaments and exhibited peripheral focal densities. The findings suggest that this glycogen-rich malignant tumor is of epithelial origin most probably of ductal cells.
Abstract. Tissues from four local recurrences of a palatal tumor and regional lymph node metastases were studied by light microscopy while ultrastructural observations were made on the most recent tumor. The tumor was composed of solid sheets, clumps, and small nests of polyhedral epithelial cells with well‐defined cell boundaries, clear cytoplasm, and cellular pleomorphism. Histochemical stains indicated the presence of abundant intracellular glycogen deposits in all tumor specimens examined. Ultrastructural observations revealed solid sheets of epithelial cells which lacked both surrounding basement lamina and ductal arrangements. The cytoplasm of the tumor cells was filled with P glycogen deposits and contained scattered bundles of tonofilaments and scant organelles. The transition between the glycogen‐rich tumor cells and surface epithelium showed intervening cells which contained diffusely dispersed ribosomes and small amounts of glycogen. The tumor probably originated from surface epithelium.
The light and electron microscopic appearances of an atypical calcifying odontogenic mandibular tumor containing "amyloid" arc presented. In a part of the tumor, PAS-reactive hyalin eosinophilic material which showed green dichroism hy polarized light after Congo Red staining, and also hematoxylinophilic mineralized portions were found. By election microscopy the hyalin material reveitled a fihrillar structure. The fihrils had a median diameter of 100 A, and were short and curved with some apparent outer nodularity. They differed morphologically from other unidentified extracellular and intracellular densely packed fihrils of ahoul 85 A in diameter, from collagen fihers and from a small numher of elastic fihers found in the connective tissue. Apparent calcification had occurred in aggregates of the 100 A fibrils to produce a linear and angulatcd electron-dense front. Calcification within epithelial cells of the tumor, and calcification in irregular foci around collagen fibers were also found.Quite different histopathological appearances were noted hy light tnicroscopy in different parts of the tumor. An anterior region eontaincd numerous Islands with large areas of odontogenic epithelium wilh peripheral amelohlast-like cells and also solid sheets of cuhoidal epithelial eells resemhllng in some ways those of the calcifying epithelial odontogenic tumor.The upper or posterior region of the tumor contained marked cavernous hemangiomatous elements separated hy a loose and often myxoid stroma. Metaplastic cartilage fotmation had occurred in one part of it. The third molar tooth was located near the coronoid notch. The tumor, although not piecisely classified, appeared to he an atypical amelohlastic fibro-odontotna.
Lipoma is the most frequent benign mesenchymal tumor that resembles normal white fat. Gastrointestinal tract lipomas are rare. The small bowel is the second predilection site of lipomas following the colon. Mesenteric lipomas mainly occur in adults without gender predilection. They are usually asymptomatic and discovered incidentally. However; these tumors may present with intussusception and intestinal bleeding. CT is the key imaging modality to diagnose mesenteric lipoma. They typically present as well-circumscribed, non-enhancing masses with homogeneous fatty attenuation, which are often contained and separate from free mesenteric fat (Figure 1 and 2: white arrows). On MRI, mesenteric lipomas demonstrate homogeneous signal intensity identical to that of fat. Thin fibrous septa of low signal intensity on T1- and T2-weighted images may be present.
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