Abstract
The intramucosal lesion of gastric signet ring
cell carcinoma (SIG) is known to form a layered
structure (LS) that simulates mucin expression
in ordinary gastric mucosa. In this study,
we suspected the influence of background
mucosa on the formation of LS and performed
histopathological analysis. We examined 35 cases
of intramucosal SIG with a maximum diameter of
30 mm or less. The LS patterns were classified
into those with a layer of MUC6-positive cells
(complete pattern, CP) and those lacking this
layer (incomplete pattern, ICP). The relationship
between LS patterns and the characteristics
of the background mucosa, the expression of
MUC2 (intestinal-type mucin antigen), MUC5AC
(foveolar-type mucin antigen), and Ki-67 (the
marker of cell proliferation activity) was examined
by histochemistry and immunohistochemistry.
Intestinal metaplasia in the background mucosa
and MUC2 expression were frequently observed
in cases with ICP. Ki-67-positive cells were much
more and they were distributed more widely in
the lesion of cases with ICP alone than in the
other cases. Mucin expression and LS formation
of gastric SIG are strongly influenced by its
background mucosa. The cases completely
lacking MUC6 expression may have higher
malignant potential.
