52 years old male with history of gastric neuroendocrine tumor

History
52 years old male with history of repeated endoscopic mucosal resection of gastric neuroendocrine tumors (G1). Elevation of chromogranin A blood levels.

Imaging findings
CT before (A) and after (B, arterial phase; C and D, portal phase) administration of contrast material show a coarsely calcified mass lesion in the tail of the pancreas. There is contrast enhancement of non-calcified components. A small lymph node with punctual calcification is present in the right-sided greater omentum. MRI before (E) and after (F, arterial phase) administration of contrast material better depicts the vascularity of the lesion. Susceptibility artifacts and partly failed fat suppression are due to gastric metallic clips after endoscopic tumor resection. DOTATOC PET-CT scan shows strong avidity of the pancreatic mass as well as of the omental lymph node.

Diagnosis
Neuroendocrine neoplasm of the pancreatic tail. Histology after left pancreatic resection revealed a neuroendocrine tumor G2 with metaplastic ossification and distant lymph node metastasis in the greater omentum.

Discussion
Calcifications are a frequent finding in neuroendocrine neoplasms of the pancreas and their metastases. Data indicate that calcifications are more frequent in G2 neoplasms than in G1 neoplasms and are associated with a higher risk of lymph node metastases and, thus, malignant behaviour.
The WHO classification system categorizes neuroendocrine neoplasms into three subtypes according to the index level of the proliferation marker Ki-67 in histology: neuroendocrine neoplasm / tumor G1 (Ki-67 index <3%), neuroendocrine neoplasm / tumor G2 (Ki-67 index 3-20%), neuroendocrine carcinoma G3 (Ki-67 index >20%).

Recommended reading
Sahani et al.
Gastroenteropancreatic neuroendocrine tumors: Role of Imaging in Diagnosis and Management
Radiology (2013) 266(1):38

provided by Tim

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