Gastrointestinal autonomic nerve tumor (GANT) in the rectum is a subset of gastrointestinal stromal tumor (GIST). It’s a very rare mesenchymal tumor with neuronal differentiation of gastrointestinal tract. We experienced a 34-year-old female patient with GANT in the lower rectum. She was referred to our hospital owing to rectal bleeding, but didn’t have other symptoms such as abdominal pain and constipation. On digital rectal examination, a round and smooth submucosal tumor at posterior wall of the rectum was palpated approximately 5 cm above the anal verge. The mass measured approximately 5 cm in diameter and was not fixed to the underlying structures. Colonoscopy, abdomino-pelvic computed tomography scan, and core needle biopsy were performed. Given the impression of GIST, it was assumed that the patient underwent low anterior resection with double stapling technique. The tumor, a yellow-grayish colored mass, was homogenous and didn’t have hemorrhagic necrosis. Diagnosis of GANT was based on histological, immunohistochemical staining, and electron microscopy. The patient did not receive any adjuvant therapy and was discharged without complications on the tenth postoperative day.
Gastrointestinal stromal tumor (GIST) is one of the most commonly found mesenchymal tumors in the gastrointestinal (GI) tract. It expresses the KIT protein. The term GIST was first used by Mazur and Clark [
Gastrointestinal autonomic nerve tumor (GANT) is a subset of GIST and a very rare mesenchymal tumor with neuronal differentiation [
A 34-year-old female was referred to our hospital because of several episodes of painless rectal bleeding. She; however, did not complain of abdominal pain, constipation or any other significant symptoms. She had no past medical history of neufibromatosis or endocrine abnormality and had undergone a cesarean section 3 years prior to this visit.
On digital rectal examination, a round and smooth submucosal tumor was palpated at posterior wall of the rectum, approximately 5 cm above the anal verge. The mass was not fixed and its diameter was approximately 5 cm. Laboratory data revealed a hemoglobin of 9.6 g/dL and normal serum levels of carcinoembryonic antigen, white blood cell and platelet count. In colonoscopy, protruded mass was covered with focally erosive epithelium in the lower rectum (
Macroscopically, the tumor was 5×4×3.5 cm in size and its mucosa had focal ulceration. The cut surface was homogenous and yellow-grayish colored. Hemorrhagic necrosis was not found (
GIST is a rare form of tumor in the GI tract, even in the omentum and mesentery [
GANT, a subset of GIST, demonstrates ultrastructural features of the autonomic nerve phenotype [
Most patients who develop GANT are between the ages of 10 and 87, with slight male predominance. It usually accompanies abdominal pain, swelling, GI bleeding, and vomiting [
Immunohistochemistry and EM can provide further supportive evidence of GANTs [
A major treatment modality is radical surgical resection with free margins [
No potential conflict of interest relevant to this article was reported.
(A) In colonoscopy, protruded mass was covered with focally erosive epithelium in the lower rectum. (B) Abdomino-pelvic computed tomography scan showed a 5 cm enhancing rectal mass (arrow) without enlarged perirectal lymph nodes. (C) The cut surface was homogenous and yellow grayish colored without hemorrhagic necrosis.
(A) The tumor cells contained plump eosinophilic cytoplasm and eccentrically located large round vesicular nuclei with prominent nucleoli (H&E, ×200). (B, C) The tumor cells were focally positive for c-kit and neurofilament respectively (immunostain, ×200). (D) Electron microscopy revealed skeinoid fibers (arrow) (×2,000).
Results of the immunohistochemical stains
Expression | Markers |
---|---|
++ | Vimentin |
+ | C-kit, S-100, synaptophysin, smooth muscle actin, neuron specific enolase, and neurofilament |
– | CD34, cytokeratin, GFAP, desmin, and chromogranin |
GFAP, glial fibrillary acidic protein.