|Year : 2013 | Volume
| Issue : 1 | Page : 138-140
Rectal adenocarcinoma coexisting with gastro-intestinal stromal tumor: A case report and literature review
Harshal Rajekar1, Amol Bhoje1, Kim Vaiphei2
1 Department of General Surgery, Post Graduate Institute of Medical Education and Research (PGIMER), Chandigarh, India
2 Department of Surgical Pathology, Post Graduate Institute of Medical Education and Research (PGIMER), Chandigarh, India
|Date of Web Publication||10-Apr-2013|
Department of General Surgery, PGIMER, Chandigarh
Source of Support: None, Conflict of Interest: None
The finding of a gastrointestinal stromal tumor along with other epithelial cancers has been previously reported. Most commonly occurring in the GI tract, a second malignancy has been reported in nearly 13-20% patients with GIST. An elderly woman with a moderately differentiated adenocarcinoma of the rectum underwent low anterior resection. Histology revealed a low-grade GIST along with adenocarcinoma of the rectum, with no lymph node involvement or metastatic disease. This seems to be the first case of a simultaneous occurrence of a GIST along with a rectal adenocarcinoma. The high incidence of a second malignancy in patients with GIST points toward an increased susceptibility to cancer. Is it necessary to treat such patients as generalized cancer syndromes with intensive surveillance and cancer screening?
Keywords: Colorectal cancer, concurrent adenocarcinoma, gastrointestinal stromal tumor, second malignancy
|How to cite this article:|
Rajekar H, Bhoje A, Vaiphei K. Rectal adenocarcinoma coexisting with gastro-intestinal stromal tumor: A case report and literature review. J Can Res Ther 2013;9:138-40
|How to cite this URL:|
Rajekar H, Bhoje A, Vaiphei K. Rectal adenocarcinoma coexisting with gastro-intestinal stromal tumor: A case report and literature review. J Can Res Ther [serial online] 2013 [cited 2020 Mar 31];9:138-40. Available from: http://www.cancerjournal.net/text.asp?2013/9/1/138/110379
| > Introduction|| |
The gastrointestinal stromal tumor (GIST) originates from primitive cells with the same characteristics as interstitial cells of Cajal (ICC), and occurs predominantly in the stomach (70%) and small intestine (10-20%). ,, Histologically, GISTs show spindle cell (70%), epithelioid (20%) or mixed morphology (10%). Activating mutations in KIT (75-80%) or platelet-derived growth factor receptor alpha (PDGFRA) (<10%) are the most common oncogenic events in GIST. ,,
The coexistence of GISTs with other epithelial cancers of different histological types is well known and the second tumor can develop synchronously or metachronously.  Of special interest are those cases in which one or more tumors were located within the same organ. This seems to be the first report wherein the simultaneous existence of a rectal GIST and a rectal adenocarcinoma within the same lesion is being reported.
| > Case Report|| |
A 62-year-old woman presented with a change in bowel habits for 1 year with per rectal bleeding for 6 months. Colonoscopy revealed a growth in the rectum and a biopsy was taken, which proved to be a moderately differentiated adenocarcinoma. Computerized tomography showed an irregular circumferential mural thickening involving the rectosigmoid colon about 12 cm from the anal verge with no enlarged draining lymph nodes [Figure 1]. Intra-operative findings included a bulky growth approx. 12-14 cm long, extending across the rectosigmoid junction. Near the distal limit of resection there was a firm, well-circumscribed nodule about 4 cm across [Figure 2], which was resected along with the rectal adenocarcinoma. A total mesorectal excision was done with a colo-anal anastomosis. Histology of the resected specimen showed the presence of a stage 2 adenocarcinoma (T3N0M0) and a c-kit positive low-grade 3.5 cm GIST in the same lesion [Figure 3] and [Figure 4]. All 15 resected lymph nodes were free of both adenocarcinoma as well as GIST. Resection margins are free of both the tumors. The postsurgical recovery was uneventful. The patient underwent a protocol CT scan at 6 months after surgery, which did not show any recurrence.
|Figure 1: Abbreviations used in the manuscript. CT scan image of the recto-sigmoid growth|
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|Figure 2: Resected specimen showing concurrent GIST and adenocarcinoma of rectum|
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| > Discussion|| |
Gastrointestinal stromal tumors are presumed to arise from interstitial cells of Cajal (ICC) and express CD117 in the majority. Ramon y Cajal described ICC about a century ago.  According to Cajal, ICC exist in all parenchymal organs, including the GI tract. According to the work of Kindblom, reported in 1998, the actual cell of origin of GISTs is a pluripotent mesenchymal stem cell programmed to differentiate into ICC.  An origin from progenitor cells of the primitive gut seems to better explain findings of muscle markers in GIST by immuno-histochemistry ,, and by molecular biologic techniques. Cells having characteristics of stem cells by the virtue of the presence of insulin-like growth factors and CD34 have been discovered and reported as the progenitor cells of ICC. All GISTs seem to derive from these stem cells within the gastrointestinal tract retaining some potential for differentiation as seen in primitive gut cells. One of the likely candidates is ICC-DMP (interstitial cells of Cajal associated with deep muscular plexus) identified as ICC having smooth muscle features. These cells have been shown to express CD117, express insulin-like growth factor and CD34, indicating their stem cell nature. 
Of late, the occurrence of a second primary malignancy in patients has received much attention as well as the syndromic association of GIST has been described. Syndromes with autosomal dominant hereditary GIST with germ line KIT or PDGFRA mutations have been reported.  Also there exist predisposition syndromes in which patients may develop GIST as well as other types of cancer. Patients with neurofibromatosis may develop GIST along with peripheral nerve sheath tumor;  in Carney's triad affected individuals may develop paraganglioma and pulmonary chordoma; and paraganglioma alone in the Carney-Stratakis syndrome. In a recent study by Ponti et al., GISTs occurred associated with other primary malignancies in 46 of 141 (32.6%) patients. 
The most common types of GIST-associated cancers were adenocarcinoma of the stomach in 9 patients, colonic cancer in 9, renal carcinoma in 4, and breast cancer in 6. Of these, 8 patients (5.6%) had a benign neoplasm including rare benign cutaneous neurofibromas, pulmonary hamartoma or GI leiomyoma. Pendurengan et al. found 153 (20%) other associated cancers (synchronous or metachronous) in 783 patients with GIST.  Other authors have reported second malignancies in patients with GIST, and even collision tumors occurring simultaneously have been reported. Microscopic GISTs can be found on histological examination specimens resected for carcinoma stomach; this incidence is 10% in specimens resected for esophageal or gastric cancer.  To our knowledge, only two cases of GISTs with rectal adenocarcinoma have been reported. The first case by Alper et al. developed rectal adenocarcinoma 5 years after treatment for rectal GIST, and in another case, carcinoma rectum was reported synchronously with a stomach GIST by Rinaldo.  Synchronous development of GIST in another viscus and adenocarcinoma of the colon has also been reported, but to our knowledge we believe that this is the first time a synchromous GIST with an adenocarcinoma of the rectum is being described. Patients with GIST have been known to sometimes harbor more than two tumors. , The percentage of GIST patients with a second diagnosed neoplasm ranges between 6 and 33%  and it is not known whether the coexistence of a GIST with other, unrelated syndromes or tumors is incidental or results from related patho-physiological processes. The germ cell theory of cancer has been largely refuted with other explanations of oncogenesis being widely researched and proven. Since GISTs probably originate in stem cells of the GI tract, the abnormality may lie in aberrant stem cells which may possibly give rise to more than one type of malignancy. The reason for the high percentage of other malignancies among patients with GIST seems to be unrelated to imatinib. Whether there is generalized microsatellite instability, or a defect in the expression of tumor suppressor genes and/or over-expression of proto-oncogenes needs to be studied and further research needs to be directed to fully understand the pathogenesis. Gene mutations or a single carcinogenic agent might interact with adjacent tissues, inducing the development of tumors of different histotypes in the same organ. The presence of a mutation or deregulated KIT expression is also observed in chronic myeloid leukemia, germ cell tumors, small cell carcinoma of the lung, neuroblastoma, melanoma, ovarian, breast and colorectal carcinoma.  There does not seem to be any mutational correlation between the GISTs and the coexistent tumors of different histological types regarding the KIT and PDGFRA genes.
| > Conclusion|| |
Many GISTs are clinically silent and therefore thorough surgical intra-abdominal exploration becomes extremely valuable in the situation. A GIST may be mistaken for a metastatic disease or a peculiar situation could arise in the liver where a focal lesion could be a metastasis or a concurrent primary tumor.
- Patients with primary GIST treated surgically or otherwise are a subset of patients who remain at a high risk of epithelial malignancy. This high incidence of a second or possibly even more cancers after the treatment of the GIST may warrant careful and increased surveillance for a second primary. Increased and intensive surveillance and screening may result in more epithelial cancers being diagnosed at an earlier stage. Further research is required in understanding the pathogenesis of this predisposition to the development of epithelial cancers in patients with GIST. Until then intensive surveillance and screening may be the only reasonable alternative in these patients.
| > References|| |
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]