Four Cases of Large Cell Neuroendocrine Carcinoma of the Stomach: Findings on CT and Barium Studies 1

Similar documents
The Spectrum of Pulmonary Neuroendocrine Carcinomas: Radiologic and Pathologic Findings 1

Abstracting Upper GI Cancer Incidence and Treatment Data Quiz 1 Multiple Primary and Histologies Case 1 Final Pathology:

Case Scenario 1. The patient has now completed his neoadjuvant chemoradiation and has been cleared for surgery.

Neuroendocrine Tumor of Unknown Primary Accompanied with Stomach Adenocarcinoma

Combined Large Cell Neuroendocrine Carcinoma and Spindle Cell Carcinoma of the Lung

Respiratory Tract Cytology

Imaging in gastric cancer

Squamous Differentiation in High Grade Large Cell Neuroendocrine Carcinoma of Ampulla of Vater

Disclosure of Relevant Financial Relationships

Stomach Computerized Tomography indications, technique, examples. VUH SK Radiology and nuclear medicine center Radiologist Dileta Rutkauskaitė

Serotonin- and Somatostatin-Positive Goblet Cell Carcinoid of the Duodenum

Immunohistochemical consistency between primary tumors and lymph node metastases of gastric neuroendocrine carcinoma

A Concurrence of Adenocarcinoma with Micropapillary Features and Composite Glandular-Endocrine. cell carcinoma in the stomach.

ESD for EGC with undifferentiated histology

Original Report. Carcinoid Tumors of the Stomach: A Clinical and Radiographic Study

A Rare Case of Gastric Carcinosarcoma with Neuroendocrine Differentiation

Case Report Five-Year Survival after Surgery for Invasive Micropapillary Carcinoma of the Stomach

Case Scenario 1: Thyroid

Diffuse Follicular Variant of Papillary Thyroid Carcinoma in a 69-Year-old Man with Extensive Extrathyroidal Extension: A Case Report

3/27/2017. Pulmonary Pathology Specialty Conference. Disclosure of Relevant Financial Relationships. Clinical History:

Disclosures. Outline. What IS tumor budding?? Tumor Budding in Colorectal Carcinoma: What, Why, and How. I have nothing to disclose

담낭에서발생한대세포신경내분비종양 1 예

Delayed Perforation Occurring after Endoscopic Submucosal Dissection for Early Gastric Cancer

Treatment Strategy for Non-curative Resection of Early Gastric Cancer. Jun Haneg Lee. Sungkyunkwan University, Samsung Medical Center, Seoul Korea

Disorders of Cell Growth & Neoplasia. Histopathology Lab

Greater Manchester and Cheshire HPB Unit Guidelines for the Assessment & Management of Hepatobiliary and Pancreatic Disease Chapter 14

C. CT scan shows ascites and thin enhancing parietal peritoneum

Case Report Intramucosal Signet Ring Cell Gastric Cancer Diagnosed 15 Months after the Initial Endoscopic Examination

Color Codes Pathology and Genetics Medicine and Clinical Pathology Surgery Imaging

CT Findings of Surgically Resected Pleomorphic Carcinoma of the Lung in 30 Patients

Metachronous solitary splenic metastasis arising from early gastric cancer: a case report and literature review

Islet Cell Tumor Arising from Heterotopic Pancreas in the Duodenum: A Case Report 1

Endoscopic Treatment of Duodenal Neuroendocrine Tumors

Central Poorly Differentiated Adenocarcinoma of the Maxilla: Report of a Case

Limited Role of Bone Marrow Aspiration and Biopsy in the Initial Staging Work-up of Gastric Mucosa-Associated Lymphoid Tissue Lymphoma in Korea

Basaloid Carcinoma of the Lung: A Really Dismal Histologic Variant?

Intrahepatic Sarcomatoid Cholangiocarcinoma with Portal Vein Thrombosis: A Case Report 1

Endoscopic Resection of Ampullary Neuroendocrine Tumor

Kentaro Tominaga, Kenya Kamimura, Junji Yokoyama and Shuji Terai

Cystic Schwannoma of the Pancreas: A Case Report 1

CASE REPORT GASTRIC ADENOCARCINOMA METASTASIS TO THE BREAST- A DIFFERENTIAL DIAGNOSIS WITH PRIMARY BREAST ADENOCARCINOMA AND REVIEW OF LITERATURE.

NEUROENDOCRINE DIFFERENTIATED BREAST CARCINOMA

Gastroenterology Tutorial

LUNG CANCER PATHOLOGY: UPDATE ON NEUROENDOCRINE LUNG TUMORS

Radiology Pathology Conference

Esophageal seeding after endoscopic ultrasound-guided fine-needle aspiration of a mediastinal tumor

Endoscopic Submucosal Dissection of an Inverted Early Gastric Cancer-Forming False Gastric Diverticulum

A Case of Early Gastric Cancer with Solitary Metastasis

Regression of Advanced Gastric MALT Lymphoma after the Eradication of Helicobacter pylori

GOBLET CELL CARCINOID. Hanlin L. Wang, MD, PhD University of California Los Angeles

GOBLET CELL CARCINOID

Case Report pissn J Korean Soc Radiol 2012;67(4): INTRODUCTION CASE REPORT

EUS FNA NEUROENDOCRINE TUMORS. A. Ginès Endocopy Unit Hospital Cínic. Barcelona (Spain)

Distant and Lymph Node Metastases of Thyroid Nodules with No Pathological Evidence of Malignancy: A Limitation of Pathological Examination

Is Hepatic Resection Needed in the Patients with Peritoneal Side T2 Gallbladder Cancer?

A Gastric Schwannoma Misdiagnosed as B Cell Lymphoma

Endoscopic Ultrasonography Assessment for Ampullary and Bile Duct Malignancy

Neuroendocrine (NE) lung tumors represent a broad

8. The polyp in the illustration can be described as (circle all that apply) a. Exophytic b. Pedunculated c. Sessile d. Frank

Case Report Gastric Endocrine Cell Carcinoma Coexistent with Adenocarcinoma

Gastric Cancer Histopathology Reporting Proforma

Gastrointestinal Tract Cancer

Case Report A Rare Cutaneous Adnexal Tumor: Malignant Proliferating Trichilemmal Tumor

Radiology Pathology Conference

Kidney Case 1 SURGICAL PATHOLOGY REPORT

The gastric carcinosarcoma with severe venous invasion: a case report

A218 : Esophagus cancer tissues. (formalin fixed)

Patient. Male 76 year old C.C: abdominal pain

Neoplasia 2018 Lecture 2. Dr Heyam Awad MD, FRCPath

malignant polyp Daily Challenges in Digestive Endoscopy for Endoscopists and Endoscopy Nurses BSGIE Annual Meeting 18/09/2014 Mechelen

A916: rectum: adenocarcinoma

PRIMARY GASTRIC LYMPHOMA: CASE REPORT WITH REVIEW OF LITERATURE

Intra-abdominal bronchogenic cyst: report of five cases

American Journals of Cancer Case Reports. A Rare Case of Rectal Metastasis from Sarcomatoid Variant of Urothelial Carcinoma: A Case Report

Images In Gastroenterology

Case: The patient is a 62 year old woman with a history of renal cell carcinoma that was removed years ago. A 2.4 cm liver mass was found on CT

Long-term Survival after Surgical Resection for Liver Metastasis from G astric Cancer: Two Case Reports

Metachronous anterior urethral metastasis of prostatic ductal adenocarcinoma

Gastric and Oesophageal Neuroendocrine tumours. Dr Tim Bracey, Consultant Pathologist MBChB PhD MRCS FRCPath

Characteristics of intramural metastasis in gastric cancer. Tatsuya Hashimoto Kuniyoshi Arai Yuichi Yamashita Yoshiaki Iwasaki Tsunekazu

Perigastric Lymph Node Metastasis from Papillary Thyroid Carcinoma in a Patient with Early Gastric Cancer: The First Case Report

Diplomate of the American Board of Pathology in Anatomic and Clinical Pathology

CASE REPORT. Introduction. Case Report. Kimitoshi Kubo 1, Noriko Kimura 2, Katsuhiro Mabe 1, Yusuke Nishimura 1 and Mototsugu Kato 1

Segmental duodenectomy with duodenojejunostomy of gastrointestinal stromal tumor involving the duodenum

Sarcomatoid (spindle cell) carcinoma of the cricopharynx presenting as dysphagia

Financial disclosures

CASE DISCUSSION ON GASTRIC CANCER BASED ON ESMO GUIDELINES

Gastric Cancer Staging AJCC eighth edition. Duncan McLeod Westmead Hospital, NSW

Neuroendocrine Lung Tumors Myers

Undifferentiated carcinoma of the gall bladder: a rare entity

NASAL SEPTUM ADENOID CYSTIC CARCINOMA: A CASE REPORT

Case 2. Dr. Sathima Natarajan M.D. Kaiser Permanente Medical Center Sunset

Fig. 1. Ileal and jejunal metastases from adenocarcinoma of the lung in 62-year-old male with a clinical history of bloody stool. A.

CT EVALUATION OF GASTRIC LESIONS:

Sarcomatoid Carcinoma of the Small Intestine: A Case Report and Review of the Literature 1 소장에생긴육종성암 : 증례보고및문헌고찰 1

Imaging of Neuroendocrine Metastases

Primary Small Cell Carcinoma Of The Bladder: A Case Report And Review Of The Literature

Surgical Management of Neuroendocrine Tumors of the Gut. Richard Hodin MD Professor of Surgery Massachusetts General Hospital Harvard Medical School

Oncocytic carcinoma: A rare malignancy of the parotid gland

Solitary Fibrous Tumor of the Kidney with Massive Retroperitoneal Recurrence. A Case Presentation

Transcription:

Four Cases of Large Cell Neuroendocrine Carcinoma of the Stomach: Findings on CT and arium Studies 1 Hee Jung Kim, M.D., Dongil Choi, M.D., Soon Jin Lee, M.D., Won Jae Lee, M.D., Sung Kim, M.D. 2, Jae J. Kim, M.D. 3, Cheol Keun Park, M.D. 4 large cell neuroendocrine carcinoma of the stomach is extremely rare. We have reviewed the medical records and imaging studies of the four patients that presented with a large cell neuroendocrine carcinomas of the stomach. On a barium study and CT imaging, a gastric large cell neuroendocrine carcinoma is depicted as an ulcerofungating tumor with minimal peritumoral infiltration and metastatic lymphadenopathy in the perigastric area. These findings are similar to findings for advanced gastric cancer, especially orrmann type II. However, a gastric large cell neuroendocrine carcinoma is highly malignant with a significantly worse prognosis than a usual adenocarcinoma. Index words : Stomach Stomach neoplasms Tomography, X-Ray Computed Fluoroscopy Carcinoma, neuroendocrine large cell neuroendocrine carcinoma of the stomach is extremely rare and represents only a small percentage of all endocrine tumors. ccording to the WHO classification of gastric tumors, there are two subtypes of gastric endocrine tumors based on the histopathological classification (1). well-differentiated endocrine tumor and poorly-differentiated endocrine carcinoma are the 1 Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, Korea 2 Department of Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Korea 3 Department of Internal Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Korea 4 Department of Diagnostic Pathology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Korea Received January 14, 2008 ; ccepted May 16, 2008 ddress reprint requests to : Dongil Choi, M.D., Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, 50 Ilwon-dong, Kangnam-gu, Seoul 135-710, South Korea Tel. 82-2-3410-2518 Fax. 82-2-3410-2559 E-mail: dichoi@smc.samsung.co.kr 607 two major types of lesions; the well-differentiated endocrine tumor is equivalent to a carcinoid and the majority of poorly differentiated endocrine carcinomas is equivalent to a small cell carcinoma. large cell neuroendocrine carcinoma, which is in the minority of poorly-differentiated neuroendocrine carcinomas, is composed of large cells having organoid, trabecular, and palisading patterns that are suggestive of endocrine differentiation (2). Primary and metastatic large cell neuroendocrine carcinomas have not been well described in the stomach because of their extreme rarity. lthough radiological studies such as CT imaging or barium studies can be useful for the determination of tumor staging and the evaluation of the morphological appearances of gastric tumors, to the best of our knowledge, there has been no radiology report describing the imaging features of a gastric large cell neuroendocrine carcinoma. We report here the appearance of primary large cell neuroendocrine carcinomas of the stomach based on barium

Hee Jung Kim, et al : Four Cases of Large Cell Neuroendocrine Carcinoma of the Stomach studies and CT imaging findings in four patients. In addition, we review the clinical outcome of the patients with a gastric large cell neuroendocrine carcinoma. Case 1 60-year-old male underwent endoscopy due to the presence of epigastric pain and dyspepsia. On en- C D Fig. 1. 60-year-old male with a large cell neuroendocrine carcinoma of the stomach.. barium study shows a 7-cm, well-marginated mass (arrows) with a large ulceration (arrowheads) at the lesser curvature of the antrum.. contrast-enhanced CT scan with negative contrast media (water) shows a large, poorly enhanced, ulcerated mass (arrows) from the mid-body to the antrum with minimal peritumoral infiltration. 2-cm enlarged lymph node was observed around the lesser curvature (data not shown). C. photograph of a resected specimen shows a 7 7 cm-ulcerated mass (arrows) from the mid-body to the antrum along the lesser curvature. On the pathology reports, it was reported that this tumor mimicked a orrmann type II advanced gastric carcinoma orrmann type II (ulcerofungating lesion). D. photomicrograph (hematoxylin and eosin staining; original E magnification, 400) of the resected specimen shows a nest of tumor (T) cells in the submucosa. Note the large cells with a polygonal shape, abundant cytoplasm and vesicular or coarse nuclear chromatin. Tumor cells were also found in the mucosal layer and serosa (data not shown). S (stroma) E. photomicrograph with synaptophysin immunochemical staining for synaptophysin (original magnification, 400) shows positive immunoexpression in the cytoplasm (arrows, dark brown color) of the tumor cells, indicative of a neuroendocrine tumor. 608

doscopy, a huge ulcerofungating mass was also seen from the mid-body to the antrum. The impression of the endoscopist was advanced gastric cancer, and an endoscopic biopsy identified a neuroendocrine carcinoma. barium study that was performed in the patient demonstrated the presence of a 7-cm, well-marginated mass with a large ulceration in the lesser curvature of the antrum (Fig. 1). The prospective radiologic report indicated orrmann type II advanced gastric cancer (an ulcero-fungating lesion) (3). CT scan depicted a large, poorly-enhanced, ulcerated mass from the mid-body to the antrum with minimal peritumoral infiltration (Fig. 1). 2-cm enlarged lymph node was also noted around the lesser curvature. There was no distant metastasis detected on the CT image. This patient underwent extended a total gastrectomy followed by adjuvant chemotherapy. t surgery, a metastatic lymph node was found in the perigastric area. On a pathological examination, large mass extension to the perigastric adipose tissue and invasion of perineural tissue were found (stage T3N1). Immunohistochemical staining demonstrated that the samples were positive for expression of synaptophysin, cytokeratin and chromogranin (Fig. 1). s there was no evidence of a neuroendocrine carcinoma involving the other organs, we diagnosed the lesion as a primary large cell neuroendocrine carcinoma of the stomach. Follow-up CT Imaging obtained from 6 months to 26 months after surgery did not show tumor recurrence. However, CT scans obtained 32 months after surgery showed the presence of massive metastatic lymphadenopathy near the anastomotic site and tumor recurrence at the anastomotic site. The patient died of disseminated metastases 83 months after surgery. Case 2 66-year-old female suffered from dyspepsia. barium study showed the presence of a 6-cm, well-defined mass with central ulceration in the anterior wall and at the lesser curvature side of the antrum (Fig. 2). prospective radiological report documented orrmann type II advanced gastric cancer. On endoscopy, a deep excavated lesion with surrounding nodular mucosa and spontaneous bleeding was seen on the anterior wall of the antrum. The pathology of the endoscopic biopsy specimen revealed a poorly differentiated adenocarcinoma. The CT scan showed a large, well-marginated, moderately enhancing, ulcerated mass with no peritumoral infiltration and multiple lymphadenopathy located along the lesser curvature of the antrum (Fig. 2). This patient underwent a partial gastrectomy. t surgery, six metastatic lymph nodes were found in the perigastric area. pathological examination of the surgical specimen showed that the mass was extended to the proper muscle. Immunohistochemical staining was positive for expression of chromogranin and synaptophysin, and the presence of a large cell neuroendocrine carcinoma was confirmed (stage T2N2). follow-up CT scan obtained 16 months after surgery showed the presence of a Fig. 2. 66-year-old female with a large cell neuroendocrine carcinoma of the stomach.. arium study shows a 6-cm, well-defined mass (arrows) with central ulceration (arrowheads) in the anterior wall and the lesser curvature side of the antrum.. contrast-enhanced CT scan shows a well defined, large, ulcerated enhancing mass (arrows) in the antrum with no peritumoral infiltration and an enlarged lymph node (arrowhead). 609

15-cm metastatic tumor in the right hepatic lobe. The patient died of progression of metastasis 18 months after surgery. Case 3 In a 63-year-old male, a barium study showed the presence of a 4-cm, well-circumscribed mass with central ulceration at the lesser curvature side of the antrum (Fig. 3). prospective radiological report indicated a orrmann type II advanced gastric cancer. CT scan showed abnormal wall thickening with moderate enhancement and minimal peritumoral infiltration located in the lesser curvature side of the antrum with several enlarged lymph nodes in the perigastric area (Fig. 3). This patient underwent a total gastrectomy without endoscopy in our hospital; the patient was referred from an outside hospital with a pathological finding of gastric cancer. t surgery, six metastatic lymph nodes were found in the perigastric area. On a pathological examination, the mass was extended to the subserosa, and endolymphatic tumor emboli were found (stage T2N2). follow-up CT scan obtained 7 months after surgery showed the presence of multiple recurrent tumors around the anastomotic area. The patient died of tumor progression 11 months after surgery. Case 4 70-year male underwent barium study because of epigastric discomfort. The barium study identified a 5- cm, well-defined mass at the lesser curvature side from the lower body to the antrum (Fig. 4). prospective radiological report documented orrmann type II advanced gastric cancer. CT scans showed diffuse wall thickening from the lower body to the antrum with minimal peritumoral infiltration and multiple enlarged lymph nodes in the perigastric area (Fig. 4). On endoscopy, a gastric tumor with uneven based, round ulceration was seen, and spontaneous bleeding was observed. pathological examination confirmed a neuroendocrine carcinoma following an endoscopic biopsy. This patient underwent a partial gastrectomy followed by adjuvant chemotherapy. t surgery, nine metastatic lymph nodes were found in the perigastric area. On a pathological examination of the resected stomach, the tumor had extended to the subserosa, and endolymphatic tumor emboli were found (stage T2N1) (Fig. 4). The last follow-up CT obtained 22 months after surgery did not show tumor recurrence. Discussion Large cell neuroendocrine carcinoma in the stomach is an extremely rare disease, and there have been no reports on the radiological findings of this disease. Neuroendocrine tumors arise from embryonal neural crest cells, which are abundant in the epithelia of the gas- Fig. 3. 63-year-old male with a large cell neuroendocrine carcinoma of the stomach.. barium study shows a 4-cm, well-circumscribed mass (arrows) with central ulceration (arrowhead) at the lesser curvature side of the antrum.. contrast-enhanced CT scan with the use of positive contrast media shows abnormal wall thickening with moderate enhancement (arrows) and minimal peritumoral infiltration located at the lesser curvature side of the antrum. Several enlarged lymph nodes were found in the perigastric area (data not shown). 610

Fig. 4. 70-year-old male with a large cell neuroendocrine carcinoma of the stomach.. barium study shows a 5-cm, well-defined mass (arrows) in the lesser curvature side of the lower body to the antrum.. contrast-enhanced CT scan with negative contrast media (water) shows diffuse wall thickening from the lower body to the antrum (arrows) with minimal peritumoral infiltration and metastatic lymph nodes (arrowheads) in the perigastric area. C. photograph of the resected specimen shows a 5 4 cm ulcerofungating mass (arrows) at the lesser curvature side from the lower body to the antrum. This tumor mimics orrmann type II advanced gastric carcinoma. Ed-highlight-it is not necessary to repeat the figure legends next to each figure. C 611 trointestinal tract and bronchopulmonary system. Highgrade neuroendocrine carcinomas, which include small cell carcinomas and large cell neuroendocrine carcinomas, are poorly differentiated tumors that resemble their counterparts arising in the bronchopulmonary system in having an aggressive behavior, a high propensity for lymph node metastases and distant metastases (47). large cell neuroendocrine carcinoma is different from a small cell carcinoma as based on cytological findings, and is characterized by the presence of large cells with a polygonal shape, low nuclear-cytoplasm ratio, coarse nuclear chromatin, high mitotic rate and frequent necrosis (2, 5, 8). Either positive immunohistochemical staining for expression of neuroendocrine markers such as neuron-specific enolase, chromogranin and synaptophysin, or an electron microscopic depiction of neurosecretory granules is indicative of a diagnosis of a neuroendocrine tumor (8). recent radiological report of two patients with gastric small cell carcinoma described that CT imaging identified poorly or moderately enhanced ulcerated masses, and barium studies showed the presence of ulcerofungating tumors (9). nother radiological study presented an ulcerofungating mass with moderate enhancement on CT in a patient with a gastric small cell carcinoma (10). These findings are similar to findings for a large cell neuroendocrine carcinoma as well as advanced gastric cancer. While a carcinoid tumor generally has a benign course, a large cell neuroendocrine carcinoma follows an aggressive course. In our series, local tumor recurrences, metastatic lymphadenopathy, or distant metastases were observed in three of four patients. These patients showed rapid disease progression and poor response to systemic chemotherapy and later died of disseminated metastases. ased on this report, with the use of a barium study and CT imaging, a gastric large cell neuroendocrine carcinoma was depicted as an ulcerofungating tumor with minimal peritumoral infiltration and metastatic lymphadenopathy in the perigastric area. These features are

similar in appearance to advanced gastric cancer, especially orrmann type II. It is difficult to make a differential diagnosis of the two-disease entities by the use of imaging findings. However, a gastric large cell neuroendocrine carcinoma is highly malignant with a significantly worse prognosis than a usual adenocarcinoma. References 1. Capella C, Solcia E, Sobin LH, rnold R. Endocrine tumours of the stomach. In Hamilton SR, altonen L. World Health Organization Classification of Tumours. Pathology and Genetics Tumours of the Digestive System. Lyon : IRC Press, 2000:53-57 2. Travis WD, Linnoila RI, Tsokos MG, Hitchcock CL, Cutler G, Jr., Nieman L, et al. Neuroendocrine tumors of the lung with proposed criteria for large-cell neuroendocrine carcinoma. n ultrastructural, immunohistochemical, and flow cytometric study of 35 cases. m J Surg Pathol 1991;15:529-553 3. Hori S, Tsuda K, Murayama S, Matsusbita M, Yukawa K, Kozuka T. CT of Gastric Carcinoma: Preliminary Results with a New Scanning Technuque. Radiographics 1992;12:257-268 4. Lee KH, Ryu S, Lee MC, Park CS, Juhng SW, Choi C. Primary large cell neuroendocrine carcinoma of the urinary bladder. Pathol Int 2006;56:688-693 5. Selvakumar E, Vimalraj V, Rajendran S, alachandar TG, Kannan DG, Jeswanth S, et al. Large cell neuroendocrine carcinoma of the ampulla of Vater. Hepatobiliary Pancreat Dis Int 2006;5:465-467 6. Matsui K, Jin XM, Kitagawa M, Miwa. Clinicopathologic features of neuroendocrine carcinomas of the stomach: appraisal of small cell and large cell variants. rch Pathol Lab Med 1998;122:1010-1017 7. Nassar H, lbores-saavedra J, Klimstra DS. High-grade neuroendocrine carcinoma of the ampulla of vater: a clinicopathologic and immunohistochemical analysis of 14 cases. m J Surg Pathol 2005;29:588-594 8. Hiroshima K, Iyoda, Shida T, Shibuya K, Iizasa T, Kishi H, et al. Distinction of pulmonary large cell neuroendocrine carcinoma from small cell lung carcinoma: a morphological, immunohistochemical, and molecular analysis. Mod Pathol 2006;19:1358-1368 9. Lee SS, Ha HK, Kim Y, Kim TK, Kim PN, Yu E, et al. Primary extrapulmonary small cell carcinoma involving the stomach or duodenum or both: findings on CT and barium studies. m J Roentgenol 2003;180:1325-1329 10. Chang S, Choi D, Lee SJ, Lee WJ, Park MH, Kim SW, et al. Neuroendocrine neoplasms of the gastrointestinal tract: classification, pathologic basis, and imaging features. Radiographics 2007;27:1667-1679 612