Radiological Case

GIST of the Duodenum and Proximal Jejunum With an Ampullary Neuroendocrine Tumor

Mohammed Mirza, MD; Joshua Boulter; Alula Tesfay, MD

Disclosures

Appl Radiol. 2020;49(5):49-51. 

In This Article

Discussion

The coexistence of a periampullary/ampullary NETs and multifocal GIST is nearly pathognomonic of NF-1.[1] Although intra-abdominal tumors are common in the setting of NF-1, the concurrence of these two entities is rare. A majority of NETs in NF-1 are nonfunctional, even in cases of histologically confirmed somatostatinomas, the most common being periampullary/ampullary NET.[2]

In most cases, NETs and GISTs are asymptomatic and found incidentally on imaging. Uncommonly, they present with abdominal pain, upper GI bleed, palpable abdominal mass, bowel obstruction, perforation and/or biliary obstruction.[3,4] Extremely rare cases of ampullary insulinoma, gastrinoma, gangliocytic paragangliomas, and adenocarcinomas associated with multifocal GISTs have been reported.[2] Peripheral nerve sheath tumors commonly occur in NF-1, and 1–3% of patients develop pheochromocytomas.[3]

These cases must be differentiated from other hereditary and nonhereditary tumor syndromes, such as multiple endocrine neoplasias, Carny triad, and Carney-Stratakis syndrome, all of which have a propensity to coexist with GIST. In this case, the ampullary tumor was well differentiated and stained positive for synaptophysin and chromogranin confirming the diagnosis of a NET (Figures 3,4). The five additional tumors had spindle cell histology and were positive for c-kit immunohistochemistry, confirming the diagnosis of multifocal GIST.

Figure 3.

H&E stains at 400x (A), CD117 immunostain (B) and gross specimen (C) of spindle cell type of gastrointestinal stromal tumor in the duodenum and proximal jejunum.

Figure 4.

H&E stains at 400x (A), synaptophysin immunostain (B) at 100x, and gross specimen of well-differentiated grade I neuroendocrine neoplasm of the ampulla of Vater (C).

GISTs are the most common gastrointestinal manifestation of NF-1, with one third of patients found to have GISTs at autopsy.[5] While cutaneous manifestations of NF-1 are generally reported earlier, GISTs present with a mean age of 53 years, 8 years earlier than the average presentation of sporadic GIST. In addition, compared to sporadic GIST associated with NF-1 are more commonly occur in the small bowel rather than the stomach, and have a smaller mean diameter, 3.8 cm vs. 7.4 cm.[4] Radiographically, the appearance of GIST varies based on size and location. Nonetheless, they appear as homogeneous soft-tissue masses with or without signs of central necrosis.

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