NEONATAL HYPERINSULINEMIC HYPOGLYCEMIA - HETEROGENEITY OF THE SYNDROME AND KEYS FOR DIFFERENTIAL-DIAGNOSIS

The two major forms of infantile persistent hyperinsulinemic hypoglyce mia require different treatments, but are difficult to differentiate d uring surgery. Indeed, one is characterized by focal adenomatous hyper plasia often macroscopically invisible, whereas the other consists of a diffuse, but discreet, beta-cell abnormality. We evaluated, in a lar ge series of persistent hyperinsulinemic hypoglycemia, the reliability of two criteria in differentiating these two forms: the mean beta-cel l nuclear radius (MNR) and the beta-cell nuclear crowding, i.e. the nu mber of nuclei per 1000 mu m(2) beta-cell (BCNC). The values of the la rgest MNR and of BCNC in cases hearing a focal lesion (respectively, 3 .27 mu m +/- 0.25 and 14.62 +/- 1.78) were significantly different fro m those in the diffuse pathology (4.25 mu m +/- 0.43 and 10.00 +/- 1.5 5). Setting the threshold value of MNR at 3.70 mu m and that of BCNC a t 12.00 enabled correct classification of 90.9% of the diffuse and 100 % of the focal forms. beta-Cell nuclear analysis can thus contribute t o a subclassification of the syndrome, not allowed by clinical or biol ogical data. If performed during surgery it could help in determining the extent of pancreatectomy necessary to cure the patient, as the dif fuse form, with abnormal nuclei in the whole pancreas, requires subtot al to near-total pancreatectomy, whereas the focal form, devoid of abn ormal insular beta-cell nuclei, can be cured by partial pancreatectomy .