Table 1

Characteristics of patients and insulinomas

PatientInsulinoma
Case patient no.Sex/age (years)Months of symptoms before operationSymptom timing (postmeal or fasting)SiteHistological typeKi-67 (%)Size (mL)β-Cell Vv (%)β-Cell mass (mg)α- or δ-CellsAmyloid depositsHK-IInsulin concentration (ng/mg)
Global (tumor)Normalized (β-cells)
Group A
 1M/368Fasting/?HeadTrabecular50.626155No>35%No40154
 2F/5950BothHeadSolid101.9601,140Rare δNoNo104173
 3F/598/120?BothBody0.944
 4M/4412PostmealHeadTrabecular216132,080No>70%No77592
Group B
 5F/6624FastingBodySolid21.8581,045Rare δRareYes4272
 6M/5812Fasting/?TailTrabecular20.873585NoNoYes266364
 7F/3810FastingBodySolid50.444175RareYes/mixed46105
Group C
 8F/8012FastingTailTrabecular20.953475NoNoYes/mixed395745
 9F/568FastingHeadSolid41.544660Rare δNoYes/mixed117265
 10F/5919FastingNeckSolid21.126285Rare δRareYes/mixed184708
  • F, female; M, male; Vv, volume density. Months of symptoms: the onset of symptoms compatible with hypoglycemia was determined according to patients’ self-reports. Case patient 3: symptoms experienced 120 months before the diagnosis of insulinoma occurred during a period of voluntary diet for weight loss. Symptom timing: defined as postmeal and fasting when symptoms occurred within 4 h of meal ingestion and >4 h after the last food intake, respectively. For case patients 1 and 6, the occurrence of postmeal hypoglycemia could be neither established nor excluded with certainty. No fixed tissue was available for histological studies in case patient 3. The percentage of β-cells positive for Ki-67 defines the grade of insulinoma, as follows: grade 1 = 0–2%; grade 2 = 3–20%. The β-cell Vv corresponds to the relative volume (%) of the tumor occupied by β-cells. Rare δ-cells = ∼1% at the most. Rare amyloid deposits = ∼1–2% of the tumor at the most. The β-cell mass was calculated from β-cell Vv and tumor size (mL = g). The normalized insulin concentration in insulinomas (ng/mg β-cells) was calculated from the global insulin concentration (ng/mg tumor) and the percentage of β-cells in the tumor (Vv).