Journal of Cancer Research and Therapeutics

: 2013  |  Volume : 9  |  Issue : 4  |  Page : 736--738

Rare case of gastrointestinal stromal tumor of the anal canal

Madhu Kumar1, Madhu Mati Goel1, Devendra Singh2,  
1 Department of Pathology, King George's Medical University, Lucknow, Uttar Pradesh, India
2 Department of Surgery, King George's Medical University, Lucknow, Uttar Pradesh, India

Correspondence Address:
Madhu Kumar
Assistant Professor Department of Pathology, King George«SQ»s Medical University, Shahmina Road, Lucknow - 226 003, Uttar Pradesh


Gastrointestinal stromal tumor (GIST) is a rare mesenchymal neoplasm of the gastrointestinal tract. GIST of anal canal is very rare representing only 3% of all anorectal mesenchymal tumors. We report an extremely rare case of GIST of the anal canal in 60-years-old man with history of irregular bowel habits with dark colored stool mixed with blood and constipation from 6 month. Diagnosis was made on the basis of histomorphological and immunohistochemical examination.

How to cite this article:
Kumar M, Goel MM, Singh D. Rare case of gastrointestinal stromal tumor of the anal canal.J Can Res Ther 2013;9:736-738

How to cite this URL:
Kumar M, Goel MM, Singh D. Rare case of gastrointestinal stromal tumor of the anal canal. J Can Res Ther [serial online] 2013 [cited 2020 Sep 21 ];9:736-738
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Gastrointestinal stromal tumor (GIST) is a rare entity with malignant potential. It accounts for 1% of all primary gastrointestinal tumors and most common gastrointestinal tumor of mesenchymal origin. [1] GIST of stomach (50-60%) is most common followed by the small intestine (20-30%), large intestine (10%), esophagus (5%), and abdominal cavity (5%). Extra gastrointestinal sites are omentum, mesentery, retroperitoneum, gall bladder, and urinary bladder. [2]

 Case Report

A 60-year-old male patient presented with the history of irregular bowel habits with the dark colored stool mixed with the blood and constipation from 6 month. Hemogram and X-ray chest was unremarkable. In upper GIT Endoscopy no abnormalities were detected. Colonoscopy and Endoscopic Ultrasonography of abdomen showed a mass with well-defined outlines in the anal canal. Computed tomography (CT) scan of lower abdomen showed irregular wall thickening of rectum and anal canal forming circumscribed soft-tissue mass with obliteration of lumen. No lymph node was found and mass was not infiltrating the surrounding tissues. On laprotomy, the mass was felt in anorectal region. Abdominoperineal resection was carried out and specimen was sent for the histopathological examination. Gross finding of resected bowel segment [Figure 1] was 7 cm in length and outer surface had fibro fatty tissue. Luminal diameter at one end was 3 cm and at other was 1.5 cm. Cut surface showed normal mucosal lining and wall thickness varies from 0.2 cm to 0.8 cm. A nodular growth was identified at anal canal end, measuring 2 cm × 1.5 cm × 1 cm, and firm and on cutting showing solid white areas with the minimal necrosis and hemorrhage. Microscopically, [Figure 2] a stromal neoplasm extending up to muscularis propria predominantly disposed in cohesive sheets and nests. Individual tumor cells showed round to oval to spindle nuclei, finely dispersed chromatin, small inconspicuous nucleoli and vacuolated cytoplasm, partly to completely surrounding the nucleus and mitotic figures were less than 5/50 high power field. Occasional areas of interlacing bundles of uniform spindle cells with fascicular arrangement with prominent nuclear palisading and perinuclear cytoplasmic vacuolation, elongated blunt end nuclei and fibrillary cytoplasm was also seen along with areas of necrosis and advised immunohistochemistry for final diagnosis. Immunohistochemical (IHC) staining showed diffuse, marked cytoplasm positivity for CD117 and negative for S-100, CD34, CD99, SMA and Pancytokeratin A [Figure 3]. We excluded Schwannoma, Ewing sarcoma, True smooth muscle tumor, Spindle cell carcinoma, and epithelial malignancy. The final diagnosis was GIST with low risk behavior.{Figure 1}{Figure 2}{Figure 3}


GISTs are specific C-KIT protein positive mesenchymal tumors that are most commonly found in stomach and small bowel. [2] They are derived from interstitial cells of Cajal. Interstitial cells of Cajal are C-KIT positive cell, activation of C-KIT or platelet-derived growth factor receptor A (PDGFRA) occurs by mutation causes Cajal cell proliferation and GIST. The biological behavior of GIST varies according to tumor size, mitotic activity and necrosis. The final diagnosis is based on the histomorphological findings and demonstration of immunoreactivity to C-KIT oncoprotein. [2] Approximately, 95% of GISTs are immunoreactive for C-KIT (CD117). [3] As well as positive for CD34, but in the present case, it was negative. Most C-KIT negative GISTs are gastric or extra-visceral GIST that are positive for the PDGFRA mutation. [4] About 85% of GISTs possess activating mutations in the C-KIT gene, whereas another 10% have activating mutations in the PDGFRA gene. [5] Approximately, 5%-10% of GISTs appears to be negative for both C-KIT and PDGFRA mutations. The Fletcher's criteria are proposed for its simplicity and wide acceptability. [1] Fletcher's criteria for measuring malignant potential of GIST are based on size of tumor and mitotic activity. [2]

The commonly accepted criteria to predict the malignancy of GIST are the mitotic activity (>5 mitotic figures/50 high power field) and the tumor size (>5 cm). [6] The differential diagnosis includes schwannoma, Ewing sarcoma, True smooth muscle tumor, Spindle cell carcinoma, and Epithelial malignancy. Schwannoma shows typical Antoni A and Antoni B areas with hyalinized blood vessels. IHC stain positive for s-100 protein. True smooth muscle tumors (leiomyosarcoma) are hypercellular tumor with haphzard arrangement of spindle cells with the high mitotic activity and necrosis. On IHC stain positive for SMA. Spindle cell carcinoma and epithelial malignancy characterized by areas of epithelial differentiation and show cytokeratin immunorectivity. The main treatment for localized GIST is segmental intestinal resection; it is still uncertain whether local or radical resection should be the appropriate surgical approach for anorectal GIST. [7] The introduction of molecularly targeted therapy combined with radiation therapy could improve the outcomes for patients diagnosed with GIST. [8] To the best of our knowledge, only eleven cases of C-KIT positive GIST of anal canal are reported in the literature. The anal GIST is representing only 3% of all anorectal mesenchymal tumors. [9] An unusual presentation of GIST of anal canal is published in English literature, which is presented without of any symptom. [10] Hence, we add one more extremely rare case of GIST of anal canal.


Before diagnosing the GIST of anal canal the differential diagnosis should be kept in mind and can be diagnosed by IHC staining. Close follow-up of patient is mandatory to be seen local recurrence or metastases.


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