—  SPECIALTY CONFERENCE  —

Gastrointestinal Pathology

Case 1 - Hereditary Diffuse Gastric Carcinoma (HDGC)

Dhanpat Jain
Yale University School of Medicine
New Haven, CT





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Clinical History:
The patient is an asymptomatic 47 year old female of Portuguese descent, who came to the gastroenterologist insisting for an upper gastrointestinal(GI) endoscopy due to a strong family history of gastric cancer. Endoscopy revealed a 1cm ulcer in the gastric cardia that appeared benign, however, biopsies revealed a signet-ring cell carcinoma. The patient underwent pre-operative staging of the tumor with EUS and CT scans. EUS suggested that the tumor was largely limited to the mucosa and possibly submucosa, with no spread elsewhere. She underwent partial proximal gastrectomy with distal esophagectomy. The esophageal and gastric margins were found to be positive on permanent sections leading to a total gastrectomy and removal of some more of the esophagus with negative margins.


Case 1 - Figure 1
Section from the edge of the gastric ulcer showing infiltration by signet-ring cells at low magnification.
Case 1 - Figure 2
Higher magnification showing the signet-ring cells.
Case 1 - Figure 3
Higher magnification showing the signet-ring cells showing the typical morphology with single large mucin vacuole and eccentrically placed nucleus .

Case 1 - Figure 4
Section from the deeper part of the gastric wall showing infiltration by tumor cells lacking a mucin vacuole and having a histiocyte-like appearance.
Case 1 - Figure 5
Immunostain for keratin AE1/AE3 showing strong positivity in the histiocyte-like tumor cells.
Case 1 - Figure 6
Section from the non-neoplastic gastric mucosa showing mild chronic gastritis and intestinal metaplasia.


Pathological/Microscopic Findings and any Immunohistochemical or Other Studies:
Grossly the gastric ulcer was shallow, without any thickening of the mucosal folds around it or thickening of the wall. The histology confirmed a signet- ring cell/ diffuse-type gastric adenocarcinoma arising at the gastric cardia. The tumor was seen infiltrating through the submucosa into the muscularis and sub-serosa, The tumor extended extensively laterally for many cms from the ulcer, including into the proximal esophagus. The tumor cells located superficially in the mucosa contained a single vacoule of intracytoplasmic mucin typical of signet-ring cells. The cells that infiltrated deeper (submuosa and muscularis propria) gradually lost this intracytoplasmic mucin and started looking more like histocytes. There was extensive fibrosis/desmoplasia associated with the tumor. Immunostains for keratins (CAM 5.2, AE1/AE3) showed strong positivity. The signet-ring cells were strongly positive for Alcian blue and Muc2 and negative for Muc 5AC. Immunostain for E-Cadherin showed weak membranous positivity throughout the tumor. The adjacent gastric mucosa showed patchy very mild chronic gastritis with focal intestinal metaplasia. There were no Helicobacter organisms identified with special stains. The gastric cancer was characterized as stage IIB(pT3N1MO). The patient has been regularly followed until now (9 years) and is alive without any recurrent or residual disease.

Differential Diagnoses:
The differential diagnosis includes sporadic signet-ring cell carcinoma and hereditary diffuse gastric cancer.

Final Diagnosis:
Based on the family history of gastric cancer in her mother and an uncle, and the occurrence of signet-ring/diffuse gastric cancer before the age of 50 years, she was diagnosed with hereditary diffuse gastric carcinoma (HDGC) however, she tested negative for germline E-cadherin mutation in 1999. Subsequently, 17 of her family members have been seen in our institution, and have been regularly followed with surveillance endoscopy and multiple biopsies. Some of the family members show mild persistent Helicobacter- negative chronic gastritis with intestinal metaplasia, but none have been found to have gastric cancer as of yet.

Case Discussion:
This case highlights several issues and problems associated with HDGC and the subsequent discussion addresses our current understanding of HDGC and addresses some of these issues.

Review of the Literature/Treatment Options (if applicable):

Epidemiology:
The incidence of gastric cancer has been decreasing. However, it still remains the 4th most common cancer, and 2nd most common cause of cancer-related death worldwide. In the United States, it constitutes the 14th most common cancer and 7th most common cause of cancer-related deaths. The decrease in gastric cancer, most noticeable in developed countries is due to the decrease in the intestinal-type of gastric cancer, while the incidence of signet-ring/diffuse-type gastric cancer has either remained unchanged or slightly increased [1]. The vast majority of gastric cancers (90%) occur in a sporadic setting, and only 10% of cases show familial clustering [2]. Familial clustering of gastric cancer has been attributed to common environmental risk factors and/or genetic factors. Only 1-3% of gastric cancers are believed to arise due to inherited predisposition to gastric cancer [3].

Genetics and molecular pathology:
Various genetic syndromes associated with an increased risk of gastric cancer include hereditary non-polyposis colon cancer (HNPCC), Li-Fraumeni Syndrome, Juvenile polyposis syndrome. Peutz-Jeghers Syndrome, Cowden syndrome, familial adenomatous polyposis (FAP), Ataxia-Telangiectasia, BRCA-1 and BRCA 2 breast/ovary cancer, Xeroderma-Pigmentosa and Werner Syndrome [4]. These syndromes are associated with various other manifestations and cancers in other organs, and the risk of gastric cancer is relatively low. It is now recognized that besides these disorders, there exists a group of disorders with inherited predisposition to primarily gastric cancer of either diffuse-type (HDGC) or intestinal-type [Familial intestinal gastric cancer (FIGC)]. In many instances the histology of the tumor remains unknown and these are simply designated as familial gastric cancers (FGC). The genetic basis of HDGC was identified in 1998 by Guilford et al who reported three Maori families in New Zealand and described diffuse gastric cancer in multiple generations with germline E-cadherin (CDH-1) mutation shown by genetic linkage analysis and mutation screening [5]. In 1999, the International gastric cancer linkage consortium defined HDGC syndrome as any family fulfilling one of the following features: a) 2 or more cases of documented diffuse gastric cancer in first - or second - degree relatives, with at least one being diagnosed before 50 years of age; or b) 3 or more cases of documented diffuse gastric cancer in first - or second-degree relatives independent of the age of diagnosis [6]. It is suggested that for populations with a low baseline incidence of gastric cancer, such as in North America, the lst criterion could be relaxed to 2 or more cases of gastric cancer in the first – or second–degree relatives with at least 1 documented case of diffuse gastric cancer before the age of 50 years. The criteria were expanded by Brook- Wilson et al (2004) to include additional cancer phenotypes associated with HDGC [7]. An elevated risk of lobular carcinoma of breast has now also been recognized in these cases [4, 8]. HDGC shows autosomal dominant pattern of inheritance, and about 30-40% of HDGC families harbour a germline mutation in CDH-1gene [9]. The CDH-1 gene is localized in the long arm of chromosome 16 and encodes for E- cadherin, a transmembrane protein that is expressed at the baso-lateral cell surface and plays a role in cell-to-cell adhesion [10]. The extra-cellular domain of the molecule takes part in the adhesion mechanism while the intracellular cytoplasmic domain interacts with the catenins (∝, β, γ, P120ctn) indirectly influencing the organization of the actin cytoskeleton. By interaction with the catenins E-Cadherin plays a role in the WNT signaling pathway and also acts as a tumor suppressor. Loss of E-Cadherin is believed to result in the loss of cell-to-cell adhesion and to promote tumor invasiveness. Altogether 68 CDH-1 germline mutations have been identified in 273 (24.9%) families with HDGC reported to date [10]. The mutations have been typed as nonsense, splice-site and frame shift mutations, and missense mutations [10]. Mutations span the entire length of the gene, and so far no hot-spots are recognized. In individuals with germline CDH-1 mutation, where only 1 of the alleles is abnormal, the histology of the gastric mucosa appears normal and E-cadherin is normally expressed. A 2nd hit is required for the inactivation of the other allele which occurs mostly via promoter hypermelthylation (epigenetic modification) and less frequently by loss of hetrozygosity (LOH) and CDH-1 mutations [11, 12]. An intragenic deletion in the wild-type allele has also been reported [13]. The tumor cells thus show absent or weak staining for E-Cadherin. A few cases with germline TP53 mutations have been reported, and recently BRCA-2 germline mutations have been identified in 21% of patients with both gastric and breast cancers [14, 15, 16]. No germline mutations in the catenins ( ∝, β, γ, P120 ctn) or other genes (RUNX3, caspase-10 and SMAD6) have been found [10]. About 70% of HDGC and 90% of FGC families screened worldwide do not show CDH-1 mutations and remain genetically unexplained [10]. The incidence of lobular carcinoma of the breast, which shares loss of E- Cadherin as the mechanism with HDGC, is increased in these families and it is estimated that the female carriers of the CHD-1 mutation have a 40% lifetime risk of developing breast cancer [8]. One case of signet-ring carcinoma of the colon has also been reported in a CDH-1 positive HDGC family, however, in general risk of colorectal or other malignancies is very low [7].

Pathology:
The tumors seem to have no site predilection in the stomach [17, 18]. They consistently show signet-ring morphology, especially in the superficial part of the mucosa and become more histiocyte like as they infiltrate deeper. The tumor cells in cases with CDH-1 mutations tend to show weak or absent membranous staining for E-cadherin. The immunostaining for cytokeratin and mucin core-polypeptides is no different from that of sporadic signet-ring cell/diffuse gastric carcinoma. In prophylactic gastrectomy specimens performed in at-risk family members, foci of carcinoma are identified in almost all patients when extensive sampling is undertaken [17, 18]. Many times the overlying mucosa appears normal and the tumor is very small, superficial and limited to mucosa. Another lesion commonly identified in such specimens is "in-situ signet-ring cell carcinoma" composed of signet-ring cells lining the gastric foveolae/glands and limited by the basement membrane. Sometimes these signet ring cells demonstrate pagetoid spread along the gastric glands or foveolae. These are considered precursor lesions for HDGC, and also show reduced or absent membranous E-cadherin staining. Non-neoplastic gastric mucosa in gastrectomy specimens may show mild chronic gastritis, focal granulomatous inflammation around collapsing glands, foveolar hyperplasia, sometimes with globoid-cell change, and vacuolization of the surface epithelium [9]. Most cases lack intestinal metaplasia or active Helicobacter pylori infection. Clinical features, management and prevention: The age of presentation in patients who clinically manifest has been extremely variable (14-85 years), even within families. The cumulative risk of developing clinically significant gastric carcinoma by the age of 80 years is estimated to be 67% for men and 83% for women [8]. Recent data may suggest that this risk is higher. Since prophylactic gastrectomy in mutation-positive family members invariably shows gastric cancer, even if at an early stage, the data implies that some individuals probably live with their cancer without ever manifesting clinical disease or any complications. The prognosis in patients with only mucosal disease following total gastrectomy is expected to be excellent, although long-term survival in HDGC still remains unknown. The patient presented here, despite nodal metastasis and stage IIB disease is doing well and is under surveillance along with her family members. She is currently free of disease after 9 years. A very important issue in HDGC is screening and surveillance of the family members, and useful guidelines for a practical approach and management have been published [10, 19]. Genetic testing and identification of at-risk individuals often allows prophylactic gastrectomy in asymptomatic individuals. In patients with identifiable CDH-1 mutation, at-risk family members can be identified by testing for germline mutations. It is suggested that family members should be tested for CDH-1 mutation in their early teens or 20s. Prophylactic total gastrectomy in mutation-positive family member is recommended after the age of 20 years. If missense mutations are identified that are considered non-pathogenic, the individuals are considered low risk carriers and can undergo clinical surveillance similar to mutation- negative patients [20, 21]. Individuals with missense CDH-1 mutations considered to be pathogenic or with truncating mutations should be advised to undergo prophylactic gastrectomy. Individuals who are surgically unfit for total gastrectomy or who refuse this option, should undergo regular clinical surveillance with knowledge of the limitations of this procedure. Individuals with biopsy proven diffuse gastric carcinoma should undergo total gastrectomy irrespective of their age. Prophylactic gastrectomy has a mortality of about 2%, and major complications have occurred in 17% of these cases. Mutation-positive female patients should also undergo appropriate screening for breast cancer [22]. As noted earlier, in about 70-90% of patients with HDGC no underlying genetic mutation is identified, and their surveillance poses significant practical issues, a situation that is exemplified by this case. The only currently available option is to perform screening upper GI endoscopy in these patients with multiple biopsies, even of normal appearing mucosa. Advanced or improved methods of visualizing the mucosa with chromoendoscopy or narrow-band imaging (NBI) may improve the chances of finding early cancer however, studies show that many tumors underlie normal mucosa and are likely to be missed [17, 23, 24]. The limitation of the screening tools should be clearly explained to these patients and their family members.

Conclusion(s):
In summary, much has been learned about hereditary diffuse gastric cancer in recent years, however, lack of an identifiable germline pathogenic mutation in a majority of families still remains a major problem leading to critical management issues.

References:
  1. Henson DE, Dittus C, Younes M, Nguyen H, Albores-Saavedra J. Differential trends in the intestinal and diffuse types of gastric carcinoma in the United States, 1973-2000: increase in the signet ring cell type. Arch Pathol Lab Med. 2004 Jul;128(7):765-70.

  2. Ekstrom AM, Serafini M, Nyren O, Hansson LE, Ye W, Wolk A. Dietary antioxidant intake and the risk of cardia cancer and noncardia cancer of the intestinal and diffuse types: a population-based case-control study in Sweden. Int J Cancer. 2000 Jul 1;87(1):133-40.

  3. Palli D, Galli M, Caporaso NE, Cipriani F, Decarli A, Saieva C, et al. Family history and risk of stomach cancer in Italy. Cancer Epidemiol Biomarkers Prev. 1994 Jan-Feb;3(1):15-8.

  4. Schrader KA, Masciari S, Boyd N, Wiyrick S, Kaurah P, Senz J, et al. Hereditary diffuse gastric cancer: association with lobular breast cancer. Fam Cancer. 2008;7(1):73-82.

  5. Guilford P, Hopkins J, Harraway J, McLeod M, McLeod N, Harawira P, et al. E-cadherin germline mutations in familial gastric cancer. Nature. 1998 Mar 26;392(6674):402-5.

  6. Caldas C, Carneiro F, Lynch HT, Yokota J, Wiesner GL, Powell SM, et al. Familial gastric cancer: overview and guidelines for management. J Med Genet. 1999 Dec;36(12):873-80.

  7. Brooks-Wilson AR, Kaurah P, Suriano G, Leach S, Senz J, Grehan N, et al. Germline E-cadherin mutations in hereditary diffuse gastric cancer: assessment of 42 new families and review of genetic screening criteria. J Med Genet. 2004 Jul;41(7):508-17.

  8. Pharoah PD, Guilford P, Caldas C. Incidence of gastric cancer and breast cancer in CDH1 (E-cadherin) mutation carriers from hereditary diffuse gastric cancer families. Gastroenterology. 2001 Dec;121(6):1348-53.

  9. Oliveira C, Seruca R, Carneiro F. Genetics, pathology, and clinics of familial gastric cancer. Int J Surg Pathol. 2006 Jan;14(1):21-33.

  10. Carneiro F, Oliveira C, Suriano G, Seruca R. Molecular pathology of familial gastric cancer, with an emphasis on hereditary diffuse gastric cancer. J Clin Pathol. 2008 Jan;61(1):25-30.

  11. Grady WM, Willis J, Guilford PJ, Dunbier AK, Toro TT, Lynch H, et al. Methylation of the CDH1 promoter as the second genetic hit in hereditary diffuse gastric cancer. Nat Genet. 2000 Sep;26(1):16-7.

  12. Machado JC, Oliveira C, Carvalho R, Soares P, Berx G, Caldas C, et al. E- cadherin gene (CDH1) promoter methylation as the second hit in sporadic diffuse gastric carcinoma. Oncogene. 2001 Mar 22;20(12):1525-8.

  13. Oliveira C, de Bruin J, Nabais S, Ligtenberg M, Moutinho C, Nagengast FM, et al. Intragenic deletion of CDH1 as the inactivating mechanism of the wild- type allele in an HDGC tumour. Oncogene. 2004 Mar 18;23(12):2236-40.

  14. Oliveira C, Ferreira P, Nabais S, Campos L, Ferreira A, Cirnes L, et al. E- Cadherin (CDH1) and p53 rather than SMAD4 and Caspase-10 germline mutations contribute to genetic predisposition in Portuguese gastric cancer patients. Eur J Cancer. 2004 Aug;40(12):1897-903.

  15. Keller G, Vogelsang H, Becker I, Plaschke S, Ott K, Suriano G, et al. Germline mutations of the E-cadherin(CDH1) and TP53 genes, rather than of RUNX3 and HPP1, contribute to genetic predisposition in German gastric cancer patients. J Med Genet. 2004 Jun;41(6):e89.

  16. Jakubowska A, Scott R, Menkiszak J, Gronwald J, Byrski T, Huzarski T, et al. A high frequency of BRCA2 gene mutations in Polish families with ovarian and stomach cancer. Eur J Hum Genet. 2003 Dec;11(12):955-8.

  17. Huntsman DG, Carneiro F, Lewis FR, MacLeod PM, Hayashi A, Monaghan KG, et al. Early gastric cancer in young, asymptomatic carriers of germ-line E-cadherin mutations. N Engl J Med. 2001 Jun 21;344(25):1904-9.

  18. Carneiro F, Huntsman DG, Smyrk TC, Owen DA, Seruca R, Pharoah P, et al. Model of the early development of diffuse gastric cancer in E-cadherin mutation carriers and its implications for patient screening. J Pathol. 2004 Jun;203(2):681-7.

  19. Fitzgerald RC, Caldas C. Familial gastric cancer - clinical management. Best Pract Res Clin Gastroenterol. 2006;20(4):735-43.

  20. Suriano G, Oliveira C, Ferreira P, Machado JC, Bordin MC, De Wever O, et al. Identification of CDH1 germline missense mutations associated with functional inactivation of the E-cadherin protein in young gastric cancer probands. Hum Mol Genet. 2003 Mar 1;12(5):575-82.

  21. Suriano G, Oliveira MJ, Huntsman D, Mateus AR, Ferreira P, Casares F, et al. E-cadherin germline missense mutations and cell phenotype: evidence for the independence of cell invasion on the motile capabilities of the cells. Hum Mol Genet. 2003 Nov 15;12(22):3007-16.

  22. Lynch HT, Grady W, Suriano G, Huntsman D. Gastric cancer: new genetic developments. J Surg Oncol. 2005 Jun 1;90(3):114-33; discussion 33.

  23. Charlton A, Blair V, Shaw D, Parry S, Guilford P, Martin IG. Hereditary diffuse gastric cancer: predominance of multiple foci of signet ring cell carcinoma in distal stomach and transitional zone. Gut. 2004 Jun;53(6):814- 20.

  24. Shaw D, Blair V, Framp A, Harawira P, McLeod M, Guilford P, et al. Chromoendoscopic surveillance in hereditary diffuse gastric cancer: an alternative to prophylactic gastrectomy? Gut. 2005 Apr;54(4):461-8.