|Year : 2015 | Volume
| Issue : 3 | Page : 662
Primary synchronous mesenteric neuroendocrine tumors: Report of a rare case with review of literature
Sulata Manjunath Kamath1, Saratchandra Pingali2, G Girish2, K Harish2
1 Department of Pathology, M. S. Ramaiah Medical College and Hospital, Bengaluru, Karnataka, India
2 Department of Surgical Oncology, M. S. Ramaiah Medical College and Hospital, Bengaluru, Karnataka, India
|Date of Web Publication||9-Oct-2015|
Sulata Manjunath Kamath
38, 18th Cross Road, Bengaluru - 560 055, Karnataka
Source of Support: None, Conflict of Interest: None
Most neuroendocrine tumors of the gastrointestinal tract are traditionally termed "carcinoid tumors." More than 90% of all gastrointestinal carcinoids are located in the appendix, small intestine, rectum, and mesenteric carcinoids are rare. Even when invasive, most carcinoids are relatively indolent and display minimal histological pleomorphism. A minority of these tumors is clinically more aggressive and has a less differentiated histological pattern. Carcinoid tumors of the intestine frequently invade the mesentery, but a primary carcinoid of the mesentery is extremely rare. Mesenteric carcinoid tumors can go unrecognized due to nonspecific symptoms. We report an unusual case of two large primary mesenteric carcinoid tumors in a 38-year-old male who had excellent recovery following surgery. A complete histopathologic, immunohistochemical, and radiologic workup enabled correct diagnosis in this case.
Keywords: DOTATOC scan, mesenteric tumors, neuroendocrine
|How to cite this article:|
Kamath SM, Pingali S, Girish G, Harish K. Primary synchronous mesenteric neuroendocrine tumors: Report of a rare case with review of literature. J Can Res Ther 2015;11:662
|How to cite this URL:|
Kamath SM, Pingali S, Girish G, Harish K. Primary synchronous mesenteric neuroendocrine tumors: Report of a rare case with review of literature. J Can Res Ther [serial online] 2015 [cited 2019 Nov 14];11:662. Available from: http://www.cancerjournal.net/text.asp?2015/11/3/662/138108
| > Introduction|| |
Carcinoid tumors are rare, slow-growing tumors depicting the property of amine precursor uptake and decarboxylation (APUD). They comprise 2% of all the gastrointestinal tumors.  Primary mesenteric carcinoid tumors are very unusual, although secondary mesenteric involvement is common, reported as 40-80%, respectively.  We present a very rare case of multifocal primary mesenteric tumors showing benign character in spite of being large sized.
| > Case report|| |
A 38-year-old male presented with history of lower abdominal pain for 2 months, gradually progressive, of dull aching type, nonradiating with no aggravating or relieving factors. No significant past medical history. Clinical examination, electrocardiography and echocardiography findings were normal.
Computed tomography (CT) revealed masses in the para-aortic region, the mass on the right side measured 82 × 85 mm with multiple cystic areas within, compressing inferior vena cava and small intestinal loops. The left sided mass measured 129 × 108 mm, with large areas of central necrosis, compressing the left kidney and small bowel loops. No lymphadenopathy noted [Figure 1]. Radiologic diagnosis of atypical presentation of mesenteric gastrointestinal stromal lesion was made. Further the patient underwent ultrasonography guided biopsy, which revealed fragments of tumor tissue with cells arranged in small nests and glandular pattern, having abundant granular cytoplasm and minimal nuclear atypia. An impression of neuroendocrine tumor was made, but the site of origin could not be commented upon. It was thought that there could be a possible pancreatic endocrine tumor which was later disproved. A month later, a DOTATOC positron emission tomography-CT (PET-CT) scan confirmed a 13.3 × 11.3 × 13 cm heterogeneously enhancing necrotic somatostatin receptor avid mass lesion at the mesenteric root compressing and displacing pancreas, left kidney and duodenojejunal flexure, most likely representing primary mesenteric neuroendocrine tumor [Figure 2].
|Figure 1: Computed tomography scan showing huge bilateral para-aortic masses|
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Subsequently, patient underwent laparotomy. On laparotomy, there were two huge mesenteric masses found. One on the posterior aspect of pancreas, 8 × 8 × 5.5 cm, nodular, encapsulated, partly cystic and solid mass, focally adherent to the duodenal serosa. Another mass involved the mesenteric root at the duodenojejunal flexure, encapsulated, measuring 18 × 16 × 6 cm, and weighing 1 kg. Specimens of Whipples procedure, para-aortic mass, and omentum were sent for histopathology.
Dissection of the pancreaticoduodenectomy specimen showed pancreas with an encapsulated, lobulated tumor. Cut surface of the tumor revealed a variegated appearance with yellowish and hemorrhagic areas, cysts, and myxoid areas [Figure 3]a. Rest of the duodenum, pancreas and gall bladder appeared unremarkable. The para-aortic mass showed features as mentioned above [Figure 3]b. Multiple sections showed a tumor with cells arranged in acinar, focally fused papillary and tightly packed trabecular pattern. The tumor cells were oval to polygonal with pleomorphic/vesicular nuclei, prominent nucleoli and eosinophilic, granular cytoplasm. Speckled nuclear chromatin was seen [Figure 4] and [Figure 5]. The tumor cells were separated by broad, hyalinized, sclerotic bands of fibrous tissue with scattered lymphoid aggregates. Lymphatic and vascular tumor emboli were seen [Figure 6]. Cystic degeneration was seen. Mitotic count was <2/10 hpfs, Ki-67 index was 10% and necrosis was 30% in both the tumors. No lymph nodes were isolated. A detailed immunohistochemical workup showed positivity of tumor cells for pancytokeratin, synaptophysin and chromogranin A [Figure 7]. The tumor cells were negative for CK7, CD20, vimentin, melan A and inhibin. Ki-67 proliferative index was 10% in the tumor [Figure 8]. In our case, there were two large sized tumors involving the mesentery at different sites. It was difficult to establish whether there were two synchronous primary tumors or contiguous metastatic deposits. The first diagnosis is the most probable one in this case. The good prognostic factors were: A low mitotic activity, a low proliferation rate; poor prognostic factors being large tumor size, necrotic foci in the tumor, and angiolymphatic invasion. Diagnosis of an intermediate grade - Grade 2 neuroendocrine tumor (or "atypical carcinoid") seemed to be the most appropriate diagnosis. At 2 months of follow-up, the patient is asymptomatic and doing well.
|Figure 3: (a) Encapsulated, partly solid, partly cystic lesion focally adherent to the duodenal wall. (b) Para-aortic mass with necrotic, hemorrhagic areas|
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|Figure 4: Photomicrograph showing tumor cells in trabecular pattern (H and E, ×100)|
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|Figure 5: Photomicrograph showing cells with nuclear speckled chromatin (H and E, ×200)|
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|Figure 6: Photomicrograph showing tumor cells among Brunner glands (H and E, ×100)|
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|Figure 7: Diffuse, granular cytoplasmic positivity for synaptophysin (immunohistochemistry, ×200)|
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|Figure 8: Tumor cells show 10% nuclear staining with Ki-67 (immunohistochemistry, ×200)|
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| > Discussion|| |
True primary solid tumors of the mesentery include primary neoplasms composed of either smooth muscle, blood vessels or fat, fibromatoses, neurofibromas, teratomas, germ cell tumors, carcinoid tumors.  In 1907, Obendorfer used the term carcinoid as an ileal tumor.  Solid tumors arising in the mesentery are usually metastatic. In our case, the tumors were partly solid and cystic. Occasional reports of primary mesenteric carcinoids are generally regarded as unproved due to insufficient definite evidence of exclusion of a primary source elsewhere.  In our case, complete endoscopic workup of the entire gastrointestinal tract revealed no evidence of any primary tumor. In conjunction with specific radiologic studies, pathologic analysis, comprehensive immunohistochemistry, primary nature of the mesenteric neuroendocrine tumors were confirmed. Of all carcinoids, 25% occur in the terminal ileum, 15% in the bronchial tree, 12% in the appendix, rare locations are the stomach, rectum, mesentery, thyroid, ovary, and testes.  The diagnosis may be delayed for years due to location of origin, slow growth of tumor or nonspecific symptoms. Most likely possibility of origin of primary mesenteric carcinoid tumor is the development from APUD cell rests located in the mesentery.  Kimchi et al. have reported a case of primary neuroendocrine tumor of the mesocolon wherein they state that mesenteric carcinoids originate from APUD cells in autonomic nerves within the mesocolon. 
On CT, mesenteric carcinoid tumors exhibit varying degrees of fibrosis, calcification, neurovascular bundle invasion, necrosis or lymph node metastasis. Characteristic smooth-contoured soft tissue mass is seen surrounded by radial bands caused by desmoplastic reaction by the tumor or neurovascular bundle invasion or both.  In our case, somatostatin receptor scintigraphy scan was specific and confirmatory for ruling out extra-abdominal focus of neuroendocrine tumor.  68 Ga-DOTATOC PET-CT scan has highest detection rate for neuroendocrine lesions in the whole body. 
Microscopically, typical carcinoid tumors have one of the five growth patterns: Insular, trabecular, glandular, undifferentiated, or mixed. In our case, the tumor showed glandular and tightly packed trabecular patterns. 
Surgical excision is the mainstay of treatment for carcinoid tumor. Larger tumors are usually associated with locally advanced or distant metastasis. For tumors larger than 2 cm with regional mesentery metastasis and lymph node involvement, wide excision of the bowel and mesentery with lymph node dissection is mandated as they are associated with high incidence of metastasis. It is also recommended for relief of symptoms and prolonged survival.  In our case, Whipple's procedure was done due to focal duodenal wall adhesion.
| > Conclusion|| |
In our case a 68 Ga PET imaging was invaluable to locate the exact site of the large tumor whose origin was unsatisfactory on ultrasound. Hence, use of specific radiologic imaging techniques is mandatory in the diagnostic workup of neuroendocrine tumors in rare locations as mesentery, stomach and rectum. Timely identification of these usually undetected tumors prevents diagnostic delays and development of carcinoid syndrome. Surgical resection is warranted considering the protracted course of the disease with minimum rate of complications and mortality.
| > Acknowledgments|| |
The authors would like to thank Dr. Vijaya V. Mysorekar.
| > References|| |
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8]