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Review
. 2021 Apr 2;100(13):e25076.
doi: 10.1097/MD.0000000000025076.

Ectopic insulinoma diagnosed by 68Ga-Exendin-4 PET/CT: A case report and review of literature

Xiaona Zhang  1   2 , Hongwei Jia  1 , Fengao Li  1 , Chunyun Fang  1 , Jinyang Zhen  1 , Qing He  1 , Ming Liu  1
Affiliations
Review

Ectopic insulinoma diagnosed by 68Ga-Exendin-4 PET/CT: A case report and review of literature

Xiaona Zhang et al. Medicine (Baltimore). .

Abstract

Rationale: Ectopic insulinomas are extremely rare and challenging to diagnose for clinicians. Precise preoperative localization is essential to successful treatment.

Patient concerns: A 23-year-old man presented with a 1-year history of recurrent hypoglycemia.

Diagnosis: Examinations in the local hospital did not reveal any pancreatic lesion. After admission, a fasting test and a 5-hour oral glucose tolerance test (OGTT) suggested a diagnosis of endogenous hyperinsulinemic hypoglycemia. Enhanced volume perfusion computed tomography (VPCT) revealed 2 nodules in the tail of the pancreas, a nodule in the gastric antrum, and a nodule in the hilum of the spleen. To differentiate which nodule was responsible for hypoglycemia, we performed 68Ga-Exendin-4 PET/CT and 68Ga-DOTATATE PET/CT which helped to make a conclusive diagnosis that the lesion in the gastric antrum was an ectopic insulinoma.

Interventions: The patient was cured with minimally invasive laparoscopic resection of the tumor.

Outcomes: The symptoms were relieved and the blood glucose level remained normal after surgery.

Conclusions: This case shows that 68Gallium-exendin-4 PET/CT is useful for precise localization and thereby successful treatment of insulinoma, especially for occult insulinomas and those derived from an ectopic pancreas.

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Conflict of interest statement

The authors have no conflicts of interests to disclose.

Figures

Figure 1
Figure 1
Pancreatic VPCT (A, B) and MRI (C) of the patient. (A)The thick arrow indicated the nodule on the right side of the gastric antrum (maximum cross-section of approximately 21 mm × 16 mm). (B)The thin arrows showed 2 small nodules in the tail of the pancreas (13 mm and 7 mm in diameter, respectively), and the short arrow showed a nodule in the hilum of the spleen. (C) The thick arrow indicated the nodule on the right side of the gastric antrum, and the thin arrows showed 2 small nodules in the tail of the pancreas.
Figure 2
Figure 2
68Ga-DOTATATE PET/CT showed increased uptake of tracer in the nodule on the right side of the gastric antrum, no abnormal concentration of tracer was seen in the pancreas (A). The nodule in the tail of the pancreas showed no abnormal concentration of tracer (B).
Figure 3
Figure 3
68Ga-Exendin-4 PET/CT showed intense uptake in the nodule on the right side of the gastric antrum, suggesting an insulinoma, no abnormal concentration of tracer was seen in the pancreas (A). The nodule in the tail of the pancreas showed no abnormal concentration of tracer (B).
Figure 4
Figure 4
18F-FDG PET/CT showed abnormal concentration of tracer in the lesion on the right side of the gastric antrum (A). The nodule in the tail of the pancreas showed no abnormal concentration of tracer (B).
Figure 5
Figure 5
(A) The tumor is separated from the exocrine pancreas by an envelope. Star indicates the tumor, the thin arrow indicates the envelope, and the thick arrow indicates the exocrine pancreas. (B) The microscopy of tumor cells. (C) Islets (thick arrows) and duct (thin arrow) in the exocrine pancreas.
Figure 6
Figure 6
(A-G) Immunohistochemical staining of the tumor showed: chromogranin A (+), Synaptophysin (+), Cytokeratin (+), Ki-67 (index approximately 3%), and Carcinoembryonic Antigen, Epithelial Membrane Antigen, CD56 (−). The GLP-1R and SSTR-2 immunostaining showed that both the exocrine pancreas (H, J) and the tumor (I, K) expressed these receptors.
Figure 7
Figure 7
Immunofluorescence results showed that the islets in the exocrine pancreas (A, C, E) were positive for insulin, proinsulin, glucagon, and somatostatin. The tumor (B, D, F) only expressed proinsulin and insulin, confirming that it was an insulinoma.
See this image and copyright information in PMC

References

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