Comment on persistent hyperinsulinemic hypoglycemia of infancy.

Sir,

We read with interest an excellent review of persistent hyperinsulinemic hypoglycemia of infancy (PHHI) by Goel and Chaudhury, recently published in the journal.[1] We would like to highlight few relevant points that may be useful to the readers.

Firstly, the authors did not comment on the cases of PHHI reported from India. After a thorough literature search, we could find less than 25 cases of congenital hyperinsulinism reported in the Indian pediatric literature.[23] Only one article reported familial clustering of eight cases in 1998.[2] A recent paper reported identification of ABCC8 splicing mutation.[3] Considering the higher incidence of PHHI in communities with a high rate of consanguinity, it is possible that many cases in our country go unreported due to lack of adequate facilities for work-up. We recently came across such a case (a 25-day old-term neonate with persistent hyperinsulinemic hypoglycemia) wherein positron emission tomography (PET) scan was not possible due to lack of the facility. However, in view of intractable hypoglycemia, we proceeded with surgery following laboratory documented hyperinsulinemia during an episode of hypoglycemia. The resected pancreatic specimen showed diffuse hyperplasia of beta islet cells on histology. Near-total pancreatectomy was successful in relieving symptomatic hypoglycemia in our case.

Secondly, though [18]F-dopa-positron emission tomography (PET) scan has been a highly sensitive tool in diagnosing PHHI, recent findings suggest that in as many as 36% cases it may be inaccurate in defining the location or size of the lesion, or both location and size, leading to inaccurate pancreatic resection.[4] A recent Japanese report also made similar observations and the authors suggested the use of ‘pancreatic percentage’ expressing the uptake of the head, body or tail as a percentage of the total maximum standardized uptake value of the whole gland to improve accuracy.[5]

Thirdly, there are several reports in the recent literature suggesting the coexistence of ectopic (extra-pancreatic) foci of nesidioblastosis with one such instance responsible for failure of surgery and need for continued medical line of management despite multiple pancreatectomies.[6] However, [18]F-dopa-PET scan can delineate the presence of such ectopic foci preoperatively and help in surgical excision of such lesions.

We thought the above stated points are worth mentioning though the review specifically highlighted the current concepts in PHHI. These reports are preliminary but it is important for the treating medical-surgical teams to bear in mind these emerging potential drawbacks of preoperative PET scan and the coexistence of ectopic foci of nesidioblastosis. One should note that intraoperative histological confirmation is invariably needed in both these instances. Studies further characterizing persistent hyperinsulinemic hypoglycemia of infancy in Indian population are warranted.