Treatment of a pancreatic endocrine tumor by ethanol injection (PEI) guided by endoscopic ultrasound

We read with interest the article by Muscatiello et al. about treatment of an endocrine pancreatic tumor by ethanol injection [1]. It underlined the potential role of this treatment, which was first described by our group in 2006 [2]. There is no explanation for why the percutaneous injection route (suggested by the term “PEI,” i. e., percutaneous ethanol injection) was chosen while using endoscopic ultrasound (EUS) for guidance. Linear EUS offers the option of direct visualization of the needle, which can be used not just for fine-needle aspiration, but for injection as well.

In addition, we note that the tumor size and the amount of ethanol used for ablation are not specified. An unbalanced ratio between these could cause damage to the adjacent pancreas. In our patient the use of a relatively large amount of alcohol (8 mL) was guided by the changed echogenicity of the tumor (diameter 13 mm). It led to a complete biochemical, clinical, and morphological remission of the insulinoma that has lasted for more than 6 years. Later, Matthes et al. [3] demonstrated that an injection of 2 mL ethanol (concentration > 40 %) into porcine pancreas creates a necrotic zone approximately 20 mm in diameter. Their data, the experience of mild pancreatitis in our patient, and the reported necrotizing pancreatitis necessitating surgery in the patient of Muscatiello et al. should remind us to keep an eye on the amount of alcohol used and the potential for lethal side effects. In view of the more or less benign behavior of these tumors, we should consider using smaller amounts for the initial injection treatment. If necessary, it is relatively easy to follow this up with a second session. Until the results of at least one controlled study are published, it must be emphasized that surgery remains the gold standard for treatment of symptomatic neuroendocrine tumors.

Competing interests: None

References

• 1 Muscatiello N, Nacchiero M, Della Valle N. et al . Treatment of a pancreatic endocrine tumor by ethanol injection (PEI) guided by endoscopic ultrasound.  Endoscopy. 2008;  40 DOI: DOI 10.1055/s-2007-95540
• 2 Jürgensen C, Schuppan D, Neser F. et al . EUS-guided alcohol ablation of an insulinoma.  Gastrointest Endosc. 2006;  63 1059-1062
• 3 Matthes K, Mino-Kenudson M, Sahani D V. et al . Concentration-dependent ablation of pancreatic tissue by EUS-guided ethanol injection.  Gastrointest Endosc. 2007;  65 272-277