Treatment of Insulinomas by Laparoscopic Radiofrequency Ablation: Case Reports and Literature Review

A rare case of insulinoma presenting with deep vein thrombosis, successfully treated with minimally invasive procedures including microwave ablation

Summary

Treatment of insulinoma can be challenging, while surgical resection is considered the first line. When surgery is contraindicated or is refused, minimally invasive procedures such as selective arterial embolization, local ablative techniques including alcohol ablation, radiofrequency ablation and microwave ablation are being used of late. The world's first microwave ablation of insulinoma was performed in 2015, after which there have been only a handful of reported cases. A 78-year-old female presented with painful swelling of the left lower limb. She was drowsy and was previously misdiagnosed as epilepsy when she had similar episodes since 2 years ago. She had hypoglycaemia with high serum insulin and C-peptide, and mildly high adjusted calcium, serum prolactin. MRI did not show pituitary adenoma. Lower limb venous duplex scan showed left lower limb deep vein thrombosis for which she was treated with anticoagulation. CT of the abdomen showed a tumour measuring 1.8 cm, located in the antero-superior aspect of the body of the pancreas, with the superior surface being abutted by the splenic artery and the inferior surface being 3 mm above the pancreatic duct, suggestive of an insulinoma. Selective transcatheter arterial embolization of the pancreatic tumour was attempted but was abandoned due to multiple small feeding arteries. Microwave ablation of the tumour was performed successfully. Since there was a possibility of the ablation being compromised due to the heat sink at the splenic artery, 2 mL of 99% alcohol was injected into the rim of the tumour near the artery. She was subsequently normoglycaemic. She defaulted follow up for repeat imaging of pancreas and screening for MEN1 syndrome due to the impact of the COVID-19 pandemic. Minimally invasive procedures are preferred over surgery in selected patients with insulinoma, out of which microwave ablation could be preferentially recommended due to its efficacy and minimal complications. We report the first case of MWA performed in combination with AA in successfully treating insulinoma to our knowledge. This is also the first reported case of DVT associated with isolated insulinoma prior to intervention, though it is rarely reported in MEN1 syndrome.

Learning points

Novel therapeutic minimally invasive procedures are successful in treating selected cases of insulinoma. Microwave ablation could be recommended preferentially over selective trans-arterial embolization, and radiofrequency ablation in treating insulinoma due to its efficacy and minimal complications. We report the first case of microwave ablation performed in combination with alcohol ablation in successfully treating insulinoma to our knowledge.

Radiofrequency Ablation as a Primary Therapy for Benign Functioning Insulinoma

Objective

Insulinomas are rare, life-threatening pancreatic neuroendocrine tumors. Surgical removal continues to be the treatment of choice, yet it is associated with considerable risk of morbidity. Here, we describe our patient with insulinoma who was successfully treated with radiofrequency ablation.

Methods

The patient was a 56-year-old man with no history of diabetes mellitus. He presented with recurrent episodes of transient ischemic attacks and stroke over the last 3 years. Some changes in his behavior and memory were noticed by family members. During his hospital stay for the second transient ischemic attack, frequent hypoglycemia was documented, which was asymptomatic. Insulinoma was confirmed biochemically. Radiological findings were also compatible with pancreatic neuroendocrine tumor. Treatment modalities were explained to the patient. However, he strongly refused surgery. Meanwhile, he was admitted because of a stroke and concurrent hypoglycemia again. In view of his refusal of the surgical treatment and due to his presentation with acute stroke and high-risk status for surgery, radiofrequency ablation was finalized.

Results

Radiofrequency ablation of the pancreatic tumor using 40.75 Gy over fractions was performed with a favorable outcome. The patient has achieved biochemical normalization and remained euglycemic during his follow- up. Computed tomography scan of the abdomen during follow-up showed a mild regression of the size of the tumor.

Conclusion

This report shows a treatment challenge that required the use of an alternative treatment option other than the standard of care. It highlights the evolving evidence of radiofrequency as a therapeutic modality for patients with insulinoma.