University Pathologists - Case of the
Month -
CASE ARCHIVE > INTRAEPITHELIAL SIGNET RING CELL CARCINOMA ARISING IN VILLOUS ADENOMA WITH HIGH GRADE DYSPLASIA
provided by Mirela Stancu, MD
A 52 year old man presented with rectal bleeding. A 1.8 cm pedunculated polyp was found
in the sigmoid colon at colonoscopy. The polyp was removed using hot snare.
The polyp was entirely submitted for histologic examination. The polyp has a villous
contour composed of long, fern-like villous projections lined by high-grade adenomatous
epithelium, histologic features that are diagnostic of villous adenoma with high-grade
dysplasia. No intramucosal carcinoma or invasive foci into the stalk of the polyp
(invasive adenocarcinoma) are noted in numerous sections and deeper levels examined. An
unusual finding is the presence of frequent nodules of intraepithelial or intraluminal
signet ring cells located within some of the deep and superficial adenomatous glands (see
photomicrographs). The malignant cells within the nodules show variable intercellular
adhesion and have the characteristic features of malignant signet ring cells: scant
cytoplasm stretched over an intracytoplasmic mucin droplet, and an excentric, crescentic
nucleus pushed at the periphery of the cell by the mucin vacuole. To rule out the
possibility of metastatic signet ring cells, immunohistochemical stains for CK7, CK20, and
CDX2 were performed. In addition, E-cadherin immunostain to evaluate for the presence or
loss of this cell-adhesion molecule was performed. The signet ring cells are positive for
CK20 and CDX2 and negative for CK7, immunoprofile that confirms their intestinal origin.
The E-cadherin showed variable staining pattern ranging from continuous, weak membranous
staining to discontinuous staining to completely absent labeling in the discohesive single
signet ring cells desquamated into the luminal space. This staining pattern suggests that
the loss and partial loss of E-cadherin cell-adhesion molecule may be responsible for the
discohesive quality of the signet ring cells, which in turn may play a role in the tumor
progression. This has been previously demonstrated in signet ring carcinoma of the
stomach.
INTRAEPITHELIAL SIGNET RING CELL CARCINOMA ARISING IN VILLOUS ADENOMA WITH HIGH GRADE DYSPLASIA
Signet ring cell carcinoma (SRCC) of the colon is rare, representing less than 2% of
the colonic adenocarcinomas. There are very few reports in the English literature
documenting the presence of signet ring cell carcinoma within adenomatous polyps (1,2,3).
Only one previous case of intraepithelial signet ring cell carcinoma within adenomatous
and non-adenomatous colonic epithelium was included in a series of 19 cases of invasive
signet ring cell carcinomas (1). In this study, most of the intraepithelial signet ring
cell carcinoma foci were associated with invasive signet ring cell carcinoma within the
same polyp or elsewhere. These reports together with the current case document the
preneoplastic - neoplastic sequence for the signet ring carcinoma, which is analogous to
the adenoma - carcinoma sequence of tumor progression established much earlier for the
conventional adenocarcinoma of colon and rectum.
Interestingly, another case report addresses the possibility of metastatic SRCC to colonic
tubular adenoma (4), emphasizing the important diagnostic role of immunohistochemical
tests.
The follow-up information for SRCC arising in association with adenomatous polyps is
available only in one case (2). The tumor had an invasive component into the submucosa of
the stalk as well as a small residual submucosal malignant focus in the colectomy specimen
(pT1N0M0). The patient was alive without evidence of metastatic disease 3 years after the
surgery.
Our case did not have any evidence of invasive carcinoma, conventional type or signet ring
cell type, and the immunohistochemical stains confirmed a primary intestinal origin of the
tumor cells (CDX2 and CK20 positive, CK7 negative). Interestingly, some of the
intraepithelial signet ring cells had discontinuous or absent membranous staining for cell
adhesion molecule E-cadherin. This finding may suggest that the loss of cell adhesion
molecules in SRCC may play a role in tumor progression, similar to SRCC of the stomach.
Clinically, due to the fact that the polyp was completely resected, no additional
treatment was offered to the patient. Surveillance of the polypectomy site is scheduled at
2 months.
1. Mai KT, et al. Intestinal epithelial lesions associated with signet ring cell
carcinoma of the colon and small intestine. Pathology 2002;34:51-56.
2. Tandon M, et al. Focus of signet ring cell carcinoma in an adenoma of the sigmoid
colon. Arh Pathol Lab Med 1999;123:957-959.
3. Nakamura T, et al. Adenoma of rectum with multiple foci of signet-ring cell carcinoma.
Dis Colon Rectum 1983;26:529-532.
4. Bismar TA, et al. Metastatic foci of signet ring cell carcinoma in a tubular adenoma of
the colon. Arch Pathol Lab Med 2003;127:1509-1512
Clinical
query on "intraepithelial+AND+signet+AND+ring+AND+cell+AND+carcinoma"
Retrieve articles specifically or generally related to the etiology,
prognosis, diagnosis or therapy of the disorder. The specialized queries below
use optimal search strategies as described by Haynes
RB et al..
<< PREVIOUS | HOME
|
