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Year : 2020  |  Volume : 63  |  Issue : 1  |  Page : 136-137
A histopathological rarity: Primary signet ring cell carcinoma arising within a colonic villous adenoma

1 Department of Pathology, Bahrain Specialist Hospital, Juffair, Manama, Bahrain
2 Department of Medical Gastroenterology, Bahrain Specialist Hospital, Juffair, Manama, Bahrain

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Date of Web Publication31-Jan-2020

How to cite this article:
Jacob S, Zayyani NR. A histopathological rarity: Primary signet ring cell carcinoma arising within a colonic villous adenoma. Indian J Pathol Microbiol 2020;63:136-7

How to cite this URL:
Jacob S, Zayyani NR. A histopathological rarity: Primary signet ring cell carcinoma arising within a colonic villous adenoma. Indian J Pathol Microbiol [serial online] 2020 [cited 2022 Jan 28];63:136-7. Available from: https://www.ijpmonline.org/text.asp?2020/63/1/136/277427

Signet ring cell carcinoma (SRCC) has been described most frequently in the stomach. It may also occur in other mucinous organs like the urinary bladder, prostate, pancreas, breast, lung etc. Within the gastrointestinal tract, up to 99% of SRCC arise in the stomach. SRCC is rare in the colorectal region as compared to the conventional adenocarcinoma, the incidence rates among all colorectal cancers ranging from 0.01% to 2.6%.[1] Even more unusual is the occurrence of a primary SRCC developing within colonic adenomatous polyps. There have been less than eight instances in literature documenting this rare phenomenon.[1],[2],[3],[4],[5],[6] This paper reports an additional case of primary SRCC arising in a colonic adenoma.

A 60-year-old male presented with 5 days history of right sided loin pain and was diagnosed to have renal colic secondary to renal calculi. He also underwent a screening colonoscopy as a routine stool examination tested positive for occult blood. There were six sessile colonic polyps of varying sizes scattered about in the colon, all of which were removed by endoscopic resection and entirely submitted for detailed histologic examination. The largest polyp was located in the sigmoid and measured 1.8 cms in maximum dimension. The other polyps ranged in size from 0.1 cm to 1.2 cms and had diverse histology i.e., hyperplastic rectal polyp, sessile serrated adenoma, tubular adenomas with low grade dysplasia and tubulo-villous adenoma with low grade dysplasia. The largest sigmoid polyp displayed a complex villous structure with filiform, broad or arborizing pattern and closely set irregular glandular structures of varying caliber with frequent branching and outpouchings [Figure 1]a and [Figure 1]b. The epithelium of the villo-glandular structures was composed of stratified columnar lining with complete loss of polarity in many foci. The nuclei of the lining cells were hyperchromatic, ovoid to round with coarse chromatin and small nucleoli [Figure 1]c. Mitotic activity was brisk with few atypical mitotic figures [Figure 1]d. Scattered about within the lining of occasional glands were dystrophic goblet cells [Figure 2]a. In some fields abundant mucin with many signet ring cells was seen streaming out from the neoplastic glands [Figure 2]b and [Figure 2]c. Also noted were small infiltrating neoplastic glands with jagged margins and singly disposed malignant cells extending deep to involve the base of the polyp [Figure 2]d. A diagnosis of primary signet ring cell carcinoma and conventional adenocarcinoma arising in a high grade dysplastic villous adenoma was made. A follow up CT scan of abdomen done was unremarkable but for cholelithiasis. As the base of the polyp was involved, the patient underwent a segmental resection of the sigmoid but no residual pathology was identified.
Figure 1: (a and b) – Complex villous structures with filiform or arborizing pattern. H and E x50. (c) – Glandular epithelium displaying high grade dysplasia with loss of polarity and increased mitotic activity. H and E x200. (d) – Atypical mitotic figure (arrow). H and E x400

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Figure 2: (a)- Dystrophic goblet cells within the dysplastic epithelial lining. H and E x200. (b)- Pools of mucin containing signet ring cells. H and E x100. (c)- High power of neoplastic signet ring cells with peripheral nuclei. H and E × 200. (d)- Small ill formed glands and singly disposed malignant cells (encircled areas) within desmoplastic stroma at the base of the polyp. H and E x100

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Colorectal adenomatous polyps often harbor foci of high grade dysplasia or conventional adenocarcinoma. However, presence of signet ring cell type of carcinoma within these colonic adenomas is highly unusual.[1],[2] In a series of 81 malignant colorectal polyps, only one case of SRCC was noted, highlighting the rarity of this type of malignant transformation within large bowel adenomas.[4] Only a handful of reports of primary SRCC arising within adenomatous colonic polyps have been identified in literature.[1],[2],[3],[4],[5],[6] The phenomenon was first described by Nakamura in 1983 who reported multiple foci of SRCC along with common type adenocarcinoma in a tubulo-villous adenoma.[2] An interesting case of primary SRCC in an adenomatous polyp developing at the site of ureterosigmoidostomy was also reported.[3] The literature also documents rare case reports of signet ring cell deposits within colonic adenomas, secondary to metastasis from carcinoma of sigmoid colon.[6]

The neoplastic cells of primary SRCC are immunoreactive for CK20 and CDX2 and negative for CK7 indicating colonic origin. Variable loss of E cadherin staining suggests that loss of cell adhesion molecules may play a role in tumor progression in SRCC.[6] The presence of both primary SRCC and separate foci of conventional adenocarcinoma was noted in the present case as well as in previous reports, establishing evidence of preneoplastic- neoplastic sequence.[1],[2],[5],[6]

Two diagnostic caveats of neoplastic signet ring cells include muciphages and benign signet ring cell change. The latter is a rare feature and has also been described in pseudomembranous colitis. It must be remembered that benign signet ring cells are always confined to the basement membrane.[7]

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

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Conflicts of interest

There are no conflicts of interest.

   References Top

Tandon M, Sostek M, Klein MA. Focus of signet ring cell carcinoma in an adenoma of the sigmoid colon. Arch Path Lab Med 1999;123:957-9.  Back to cited text no. 1
Nakamura T, Nakano G, Sakamoto K. Adenoma of the rectum with multiple foci of signet ring cell carcinoma. Dis Colon Rectum 1983;26:529-32.  Back to cited text no. 2
Sohn M, Füzesi L, Deutz F, Lagrange W, Kirkpatrick JC, Braun JC. Signet ring cell carcinoma in adenomatous polyp at site of ureterosigmoidostomy 16 years after conversion to ileal conduit. J Urol 1990;143:805-7.  Back to cited text no. 3
Geraghty JM, Williams CB, Talbot IC. Malignant colorectal polyps: Venous invasion and successful treatment by endoscopic polypectomy. Gut 1991;32:774-8.  Back to cited text no. 4
Mai KT, Isotalo PA, Guindi M, Burns BF, Parks W. Intestinal epithelial lesions associated with signet ring cell carcinoma of the colon and small intestine. Pathology 2002;34:51-6.  Back to cited text no. 5
Stancu M. Intraepithelial signet ring cell carcinoma arising in villous adenoma with high grade dysplasia. www.universitypathologists.com/education/case-of...../august-2010.  Back to cited text no. 6
Jacob S, Zayyani NR. Benign signet ring cells in pseudomembranous colitis: A diagnostic trap. Indian J Pathol Microbiol 2013;56:413-5.  Back to cited text no. 7
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Correspondence Address:
Sunitha Jacob
Bahrain Specialist Hospital, Juffair, Manama
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/IJPM.IJPM_811_18

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