Case Author(s): Christian T. Schmitt, M.D. and Keith Fischer, M.D. , 8/20/02 . Rating: #D2, #Q3

Diagnosis: Neuroendocrine Carcinoma of the Pancreas

Brief history:

74 year old man with chronic epigastric pain increasing over past 3 weeks.

Images:

Anterior and posterior images are shown

View main image(ot) in a separate image viewer

View second image(ot). Axial SPECT images

View third image(ct). Limited images from abdominal CT

Full history/Diagnosis is available below

Diagnosis: Neuroendocrine Carcinoma of the Pancreas

Full history:

The patient was initially evaluated with abdominal ultrasound at an outside hospital which showed a pancreatic mass. This was followed by endoscopic retrograde cholangiopancreatography(ERCP) with endoscopic ultrasound which demonstrated a 2.5cm x 1.7cm hypoechoic pancreatic neck mass and a 1.1cm peripancreatic lymph node which were biopsied. The cells were atypical and positive for synaptophysin consistent with a neuroendocrine tumor. Abdominal CT demonstrated dilatation of the pancreatic duct with pancreatic atrophy, but did not identify a definite mass. The whole body octreotide scan was being performed for staging.

Radiopharmaceutical:

In-111 Pentetreotide (Octreotide)

Findings:

CT: Atrophic pancreas with a dilated pancreatic duct. No definite mass.

ERCP with endoscopic US (not shown): 2.5cm x 1.7cm hypoechoic pancreatic neck mass and a 1.1cm peripancreatic lymph node

Octreoscan: Two foci of increased activity in the pancreatic neck region corresponding to the hypoechoic mass and lymph node seen on US. No distant metastases.

Discussion:

Somatostatin is a neuropeptide that exists in 14- and 28-amino-acid molecular forms. It inhibits the release of several hormones, including growth hormone. Gastro-entero-pancreatic neuroendocrine tumors are relatively rare, and pancratic endocrine tumors are even more rare. These neuroendocrine tumors have a high density of somatostatin receptors. Octreoscan is a radiolabeled form of the somatostatin analog octreotide that shares the receptor binding site as naturally occurring somatostatin. This allows for imaging of neuroendocrine tumors. There are 5 known subtypes of somatostatin receptors and different tumors may express variable amounts of each receptor resulting in variable sensitivity. Octreoscan has the highest affinity for the somatostatin receptor subtype 2 (SSRT2) and to a slightly smaller degree, the somatostatin receptor subtype 5 (SSRT5). The tumors that present clinically can often be metastatic at time of presentation. Octreoscan is useful in the process of staging these patients and can occasionally detect patients with previously unsuspected MEN-I syndrome.

Followup:

Subsequent to the scan, the patient underwent an exploratory laparotomy with a Whipple procedure. At the time of surgery the mass in the pancreatic neck was identified along with a severe surrounding desmoplastic reaction. Several enlarged lymph nodes were identified as well. The pancreas was also noted to be atrophic with a markedly dilated pancreatic duct(12mm). Surgical pathology revealed a well-differentiated neuroendocrine carcinoma with peripancreatic soft tissue, lymphovascular, and perineural invasion. The surgical margins were free of tumor. Five of six peripancreatic lymph nodes were positive for metastatic neuroendocrine carcinoma. Surgical pathologic staging was Stage III(T3N1Mx). The patient experienced symptoms related to delayed gastric emptying postoperatively with reflux and emesis. The patient required readmission for the same symptoms one week later, but was eventually able to tolerate the post-gastrectomy diet and was subsequently discharged without problems.

Differential Diagnosis List

1. Neuroendocrine tumors (including: pituitary, pancreatic islet cell, paraganglioma, pheochromocytoma, neuroblastoma, medullary thyroid carcinoma, carcinoid, small cell lung cancer, Merkel cell carcinoma)

2. Brain tumors (esp. meningioma and astrocytoma)

3. Breast cancer

4. Processes with activated leukocytes (lymphoma, sarcoid, autoimmune disorders, granulomas)

ACR Codes and Keywords:

References and General Discussion of Octreotide Scintigraphy (Anatomic field:Gasterointestinal System, Category:Neoplasm, Neoplastic-like condition)

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Case number: ot007

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