Appendiceal gastrointestinal stromal tumor

Incidental lesions in appendectomy specimens: Rare or rarely sampled?

OBJECTIVE:

During the microscopic examination of the specimens after appendectomy operations performed due to acute appendicitis, pathologists may encounter some incidental and unusual lesions. Appendectomy specimens are sampled as 3 sections/1 paraffin block in many centers. In this study, we aimed to evaluate whether multiple and dense sampling of appendix specimens has an impact on the incidence of incidental lesions of the appendix.

METHODS:

This study is a retrospective study of 1154 patients who underwent appendectomy with presumed acute appendicitis at the Department of General Surgery, Istanbul University-Cerrahpasa, Cerrahpasa Faculty of Medicine, had histopathological evaluation between 2007–2011 and 2014–2018. Group 1 was made up of the patients whose appendix specimens were examined as 3 sections/1 paraffin block. Group 2 was made up of the patients whose appendix specimens were sampled completely. In this study, it was evaluated whether there was a difference between the two groups concerning incidence of incidental benign and malign appendix lesions.

RESULTS:

There were 579 patients in Group 1, 575 patients in Group 2, and the mean age of the groups was 26 and 28, respectively. Neither acute appendicitis findings nor any of the other unusual lesions were found in 57 specimens (9.8%) in Group 1 and 58 specimens (10.1%) in Group 2. Unusual pathological findings were detected in six specimens in Group 1 and 21 in Group 2. All unusual lesions, including benign and malignant, were significantly higher in Group 2 than in Group 1 (p=0.013). Concerning the incidence of malignant incidental lesions alone, there was no significant difference between the two groups (p=0.136).

CONCLUSION:

Multiple and dense sampling of appendectomy specimens increases the likelihood of detecting unusual lesions of the appendix.

Clinicopathological characteristics and prognosis of primary appendiceal stromal tumors

Background

Gastrointestinal stromal tumors (GISTs) account for less than 1% of all gastrointestinal tumors. The biological behaviors of GISTs vary from benign to malignant. GISTs are common in the stomach (55.6%) and small intestine (31.8%), but rarely in the rectum, colon (6%), and other sites (5.5%). Currently, the majority of published reports of primary appendiceal stromal tumors (PASTs) are case reports or case series.

Methods

The PASTs described in this study were identified from a literature review (23 cases) and our center (one case). The relationship between PAST gross types and clinicopathological factors was analyzed and summarized. At the same time, the study also analyzed the related risk factors and survival of PASTs and GISTs.

Results

Twenty-four cases of PASTs were compared with 254 cases of GISTs from our center. The results showed that there was a significant difference between the two groups in tumor size (P < 0.001), histological type (P = 0.013), CD34 expression (P < 0.001), and DOG-1 expression (P < 0.001). Disease-free survival (DFS) analysis of 11 cases of PASTs and 227 cases of GISTs found that a comparison of 3-year and 5-year DFS was not statistically significant (P = 0.894 and P = 0.846, respectively). In the DFS multivariate analysis, tumor mucosal ulceration, tumor size, and NIH risk classification were independent prognostic factors in 3-year and 5-year DFS.

Conclusion

In this study, there was no significance in the survival of patients with appendix and gastric stromal tumors, which we hypothesized to be associated with the low sample size and incomplete follow-up records. Based on this, we conclude that the prognosis of primary appendiceal stromal tumors may be better than gastric tumors, but this needs to be confirmed in further prospective studies.

Giant gastrointestinal stromal tumor of the vermiform appendix: A case report

Gastrointestinal stromal tumors (GISTs) of the vermiform appendix are rare, measuring <3 cm in 82.4% of the reported cases. Neoadjuvant therapy with the receptor tyrosine kinase inhibitor imatinib mesylate has the potential to improve resectability and organ preservation rates in locally advanced or metastatic/recurrent GISTs. We herein report the case of a 67-year-old male patient with an unusually large GIST (22 cm in diameter) of uncertain origin in the right lower abdominal quadrant, with a solitary peritoneal metastasis. Due to the size of this GIST and presence of metastatic disease, neoadjuvant therapy with imatinib (400 mg/day orally) was administered. Follow-up imaging studies revealed marked shrinkage of the primary and metastatic tumors. Subsequently, laparoscopic exploration revealed that the main tumor originated from the tip of the vermiform appendix, and that the peritoneal metastasis was located in the ascending mesocolon. The patient underwent laparoscopic appendectomy and excision of the peritoneal metastasis, without tumor rupture. Therefore, in appropriately selected patients, neoadjuvant imatinib for borderline resectable or oligometastatic GISTs may be a reasonable choice.

Gastrointestinal stromal tumor of the vermiform appendix mimicking Meckel's diverticulum: Case report with literature review

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We present the case of gastrointestinal stromal tumor of the vermiform appendix mimicking Meckel’s diverticulum on CT image.

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Primary appendiceal GISTs are extremely rare, with only 15 reported cases in the English literature to date.

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Rare tumors of appendix including GISTs should be considered in the differential diagnosis of atypical symptoms or image findings.

Introduction

Gastrointestinal stromal tumors (GISTs) of the appendix are extremely rare. To date, only 15 cases have been reported in the English literature. Here, we present a new case of an appendiceal GIST with appendicitis.

Presentation of case

A 68-year-old man who complained of right lower abdominal tenderness underwent surgery for a cystic mass mimicking Meckel’s diverticulum. Laparoscopy revealed a mass protruding from the proximal appendix with distal appendicitis. Complete resection with adequate margins was performed. Histology showed a spindle cell GIST without mitotic activity as well as a strong expression of CD117 and CD34.

Conclusion

Primary appendiceal GIST occur at a very low rate and their symptoms are nonspecific. Accordingly, rare tumors of appendix including GISTs should be considered in the differential diagnosis of atypical symptoms or image findings.

Appendiceal GIST: report of an exceptional case and review of the literature

Gastro-intestinal stromal tumors (GISTs) of the appendix are a rare entity. To date, only eight cases has been described in the literature, most of which have been of the benign type. We report a new case of an appendiceal GIST in a 75-year-old man. The tumor was discovered when the patient presented with acute appendiceacal peritonitis. Preoperative diagnosis of appendiceal GIST was rarely done as tumors were usually associated with appendicitis-like symptoms.

A novel complex KIT mutation in a gastrointestinal stromal tumor of the vermiform appendix

Gastrointestinal stromal tumors of the vermiform appendix are rare. To date, only 11 cases have been reported in the English literature. Here, we present a new case of appendiceal gastrointestinal stromal tumor associated with complete situs inversus. A 48-year-old man was operated on due to appendicitis-like symptoms. Laparotomy revealed a ruptured conglomerate tumor in the lower abdomen associated with extensive peritoneal adhesions. Histology showed a spindle cell gastrointestinal stromal tumor with prominent sclerosis and calcification without low mitotic activity. The tumor cells expressed strongly CD117 and CD34. The mutation analysis revealed a heterozygous deletion/insertion involving exon 11 of KIT (pK558_V559delNNins). Because the tumor was ruptured intraoperatively, a high risk was assigned according to the revised National Institute of Health criteria and adjuvant therapy with imatinib mesylate was recommended. The patient is currently alive without evidence of progression 27 months after surgery.

Unusual histopathological findings in appendectomy specimens: A retrospective analysis and literature review

AIM: To document unusual findings in appendectomy specimens.

METHODS: The clinicopathological data of 5262 patients who underwent appendectomies for presumed acute appendicitis from January 2006 to October 2010 were reviewed retrospectively. Appendectomies performed as incidental procedures during some other operation were excluded. We focused on 54 patients who had unusual findings in their appendectomy specimens. We conducted a literature review via the PubMed and Google Scholar databases of English language studies published between 2000 and 2010 on unusual findings in appendectomy specimens.

RESULTS: Unusual findings were determined in 54 (1%) cases by histopathology. Thirty were male and 24 were female with ages ranging from 15 to 84 years (median, 32.2 ± 15.1 years). Final pathology revealed 37 cases of enterobiasis, five cases of carcinoids, four mucinous cystadenomas, two eosinophilic infiltrations, two mucoceles, two tuberculosis, one goblet-cell carcinoid, and one neurogenic hyperplasia. While 52 patients underwent a standard appendectomy, two patients who were diagnosed with tuberculous appendicitis underwent a right hemicolectomy. All tumors were located at the distal part of the appendix with a mean diameter of 6.8 mm (range, 4-10 mm). All patients with tumors were alive and disease-free during a mean follow-up of 17.8 mo. A review of 1366 cases reported in the English literature is also discussed.

CONCLUSION: Although unusual pathological findings are seldom seen during an appendectomy, all appendectomy specimens should be sent for routine histopathological examination.

Gastrointestinal stromal tumors of the vermiform appendix: clinicopathologic, immunohistochemical, and molecular study of 2 cases with literature review

Gastrointestinal stromal tumors (GIST) are rare in the vermiform appendix. Only 5 cases have been reported so far, all being 14 mm or less, and they have yet not been investigated at the molecular level. Here, we report 2 appendiceal gastrointestinal stromal tumors in a 78-year-old woman and a 72-year-old man with a history of endometrial adenocarcinoma and urinary bladder carcinoma, respectively. The first patient had a history of pelvic irradiation. Both gastrointestinal stromal tumors were incidental findings at surgery for appendicitis-like symptoms and on follow-up for bladder carcinoma, respectively. Tumors were 5 and 25 mm and were located in the mid portion and the tip, respectively. The larger gastrointestinal stromal tumor was pedunculated. Both revealed a spindle cell histology with variable stromal hyalinization and occasional skeinoid fibers in 1 case. Immunohistochemistry showed reactivity for CD117 and CD34 and loss of p16 in both. Case 2 overexpressed the catalytic subunit of the human telomerase reverse transcriptase immunohistochemically. Molecular analysis of KIT revealed a missense mutation K558R in case 1 and an in-frame deletion I571_R588 in case 2, both in the juxtamembrane domain (exon 11). Comparative genomic hybridization was successful in case 2 (larger lesion) and revealed no chromosomal imbalance. We suggest that the molecular pathogenesis of appendiceal gastrointestinal stromal tumors beyond initiating KIT mutations might be different from their gastric and intestinal counterparts. The coincidence of loss of p16 and overexpression of human telomerase reverse transcriptase seems to be in contradiction to the small size, the benign nature, and the limited growth potential of appendiceal gastrointestinal stromal tumors.

Gastrointestinal stromal tumors: pathology and prognosis at different sites

Gastrointestinal (GI) stromal tumors (GISTs) are the most common mesenchymal tumors specific to the GI tract, generally defined as KIT (CD117)-positive tumors with a characteristic set of histologic features. These tumors, derived from Cajal cells or their precursors, most commonly occur at the age >50 years in the stomach (60%), jejunum and ileum (30%), duodenum (4-5%), rectum (4%), colon and appendix (1-2%), and esophagus (<1%), and rarely as apparent primary extragastrointestinal tumors in the vicinity of stomach or intestines. Their overall incidence has been estimated as 10 to 20 per million, including incidental minimal tumors. GISTs are rare in children (<1%) and almost exclusively occur in stomach. They are common in patients with neurofibromatosis 1, who have a predisposition to (multiple) small intestinal GISTs. GISTs contain a spectrum from minute indolent tumors to sarcomas at all sites of occurrence. Their gross patterns are diverse, including nodular, cystic, and diverticular tumors. External involvement of pancreas and liver can simulate primary tumor in these organs. In general, gastric tumors have a more favorable prognosis than the intestinal ones with similar parameters. Gastric GISTs < or =10 cm and < or =5 mitoses per 50 HPFs have a low risk for metastasis, whereas those with >5 per 50 HPFs and >5 cm in diameter have a high risk for metastasis. In contrast, all intestinal GISTs >5 cm independent of mitotic rate have at least moderate risk for metastases, and all >5 mitoses per 50 HPFs have a high risk for metastases. Intestinal GISTs < or =5 cm with < or =5 mitoses per 50 HPFs have a low risk for metastases. Gastric GISTs can be divided into histologic subgroups including 4 spindle cell and 4 epithelioid variants. Intestinal GISTs are a histologically more homogeneous group and often contain distinctive extracellular collagen globules, skeinoid fibers. Immunohistochemical demonstration of KIT, CD34, or protein kinase theta positivity helps to properly identify these tumors.