Endocrine Abstracts

Introduction: Insulinoma, despite its low incidence of 0.4%, it is the most common functioning pancreatic neuroendocrine tumor. Most are benign, solitary and sporadic. Around 10% can be malignant and 5-10% are part of MEN-1. On certain occasions, the differential diagnosis is difficult when there is a history of Diabetes Mellitus (DM). Our objective was to describe clinical-epidemiological data and its diagnostic-therapeutic management.

Materials and Methods: Retrospective study that used electronic records of 21 patients with a diagnosis of insulinoma confirmed by pathological anatomy treated at our Hospital from 2000-2020. Qualitative variables were described in frequencies. Shapiro-Wilk test was used to determine the normality of the variables. Data were represented according to median and interquartile range(p25-p75).

Results: 76.2% were women. The median age was 57 years(50-74). A median prior to diagnosis was 12 months(5-24). Of note, 3 patients had a previous history of DM2 and 16.7% had MEN-1. Within the laboratory parameters at diagnosis: basal insulin 18 mui/ml(11-37.9), basal C-peptide 1.61 ng/dl(1.1-2.3) and basal glucose 47 mg/dl(37-63). The most used functional test was the 72-hour fasting test; positive in all cases and in the first 24 hours(75%) and the rest in 24-48 hours (25%). Regarding non-invasive preoperative localization studies: the most application and with the best rate of correct localization was computed tomography (TC) (88.9% and 93.8% respectively), followed by magnetic resonance (RM) (42.9%) and abdominal ultrasound(19%). With a registered median size of 1.50 cm(1.3-2.1). The most frequent invasive preoperative localization study was ultrasound endoscopy(9.5%) and the most used intraoperative study was ultrasound(28.6%), which identified the tumor in all the patients. The treatment of choice was surgery in 90.4%; the majority surgical method was open approach(60%). The most frequent surgical complication was pancreatic fistula(17.6%). Four cases(20%) of malignant insulinomas were reported, all were multicentric and metastatic, predominant localization was liver. In relation to the pathological anatomy report, most were unicentric, most prevalence positive immunohistochemical markers were synaptophysin, chromogranin A and insulin. Ki67% had a median of 2%(1.5-5). The most common location was head and body(50%). Cure rates of 94.11% in benign cases and 25% in malignant cases were reported. No recurrences were recorded.

Conclusions: Insulinoma is a rare pancreatic tumor. CT or MRI are preferred non-invasive localization tests. The choice of treatment is pancreas-preserving surgery with a high cure rate. However, its morbidity and mortality increases when it is a malignant insulinoma.