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Clear cell carcinoid tumor
of stomach. A variant mimicking gastric xanthelasma.Arch
Pathol Lab Med. 1997 Oct;121(10):1100-3.
We report a rare
case of gastric carcinoid composed entirely of clear cells with foamy
cytoplasm. The patient was a 75-year-old Hispanic woman with atrophic fundic
(oxyntic) gland gastritis leading to hypochlorhydria, secondary
hypergastrinemia, endocrine cell hyperplasia, and multiple gastric
carcinoids. Grossly, the lesion was yellow and distinct from other
carcinoids in the gastric mucosa, mimicking gastric xanthelasma.
Histologically, the tumor consisted of uniform clusters of polygonal cells
with foamy cytoplasm. The formation of cell packets and abundant vascular
stroma provided clues to its neuroendocrine nature. This was confirmed by
immunoreactivity for chromogranin A and the demonstration of dense core
granules ultrastructurally.
Helicobacter pylori
infection in gastric xanthomas: immunohistochemical analysis of 145 lesions.Pathol
Int. 1996 Aug;46(8):589-93.
A total of 145
paraffin-embedded biopsy samples of gastric xanthoma were analyzed for the
localization of Helicobacter pylori (HP) antigens. By the indirect
immunoperoxidase method using a polyclonal antibody, HP infection was
identified on the surface of foveolar cells in 69 (48%) samples. In 38 (55%)
of the 69 lesions, the HP antigens were demonstrated in the cytoplasm of
xanthoma cells clustered in the actively inflamed lamina propria mucosae.
Among the remaining 76 xanthoma lesions negative for HP infection on the
epithelial surface, only eight (11%) showed the existence of HP antigens in
the foamy histiocytes, and 39 (51%) revealed mild inflammatory change.
Monoclonal antibody study using 75 specimens also gave a comparable result.
Pre-embedding immuno-electron microscopy using paraffin sections revealed
positively labeled rod-shaped bacteria both on the epithelial surface and in
the phagosome of the xanthoma cells. These findings strongly suggest that
some of the xanthoma lesions are provoked by lamina proprial invasion of
surface-infected HP.
Lipid islands in human
gastric mucosa: morphological and immunohistochemical findings.
Gastroenterology. 1996
Feb;110(2):369-74.
BACKGROUND & AIMS:
Lipid islands are a common finding in the gastric mucosa, but their
pathogenesis has not yet been established. The aim of this study was to
investigate the morphology and immunophenotype of the various cells in lipid
islands and to consider the possible mechanisms involved in the pathogenesis
of these lesions. METHODS: Morphological and immunohistochemical
investigations using antibodies against macrophages, smooth muscle cells,
and lymphocytes were performed. Unfixed tissue was available for
immunostaining for low-density lipoprotein (LDL) and oxidized LDL in one
case. RESULTS: The lipid islands were composed of KP1-, KiM1p-, and
cathepsin D-positive foam cells that were only weakly reactive for lysozyme.
In cryostat sections, the foam cells were found to contain LDL and oxidized
LDL. A few smooth muscle cells, plasma cells, lymphocytes, pericytes,
fibroblasts, and Schwann cells that contained lipid droplets were also
found. CONCLUSIONS: In gastric lipid islands, the presence of oxidized LDL,
which is taken up by macrophages and smooth muscle cells via scavenger
receptors, suggests that oxidized LDL is of key significance in the
development and persistence of these lesions. Because the metabolism of LDL
to oxidized LDL may occur by various mechanisms, various different initial
conditions, including gastritis, may precede the development of lipid
islands. Thus, anti-inflammatory treatment may be appropriate.
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