[Costello syndrome: clinical aspects and tumor risk]

Hyperinsulinemic Hypoglycemia in a Patient with Costello Syndrome: An Etiology to Consider in Hypoglycemia

Several endocrine disorders have been defined in patients with Costello syndrome (CS). In this report, we describe a patient with CS accompanied by a clinical picture of hyperinsulinemic hypoglycemia responsive to diazoxide treatment. A 41-day-old female patient with a birth weight of 3,600 g was referred for atypical facial features and swallowing dysfunction. She had a weight of 4,000 g (-0.8 SDS), a length of 50 cm (-2.4 SDS), and a head circumference of 38 cm (0.2 SDS). The clinical findings were suggestive of a genetic syndrome, mainly a RASopathy or Beckwith-Wiedemann syndrome. Whole exome sequencing revealed a de novo heterozygous missense variant in the HRAS (NM_001130442) gene in exon 2: c.35G>C; p.(Gly12Ala), establishing the molecular diagnosis of CS. The patient developed symptomatic hypoglycemia (jitteriness and sweating) at the age of 13 months. The patient's serum glucose was 38 mg/dL with simultaneous serum insulin and C-peptide levels, 2.8 μIU/mL and 1.8 ng/mL, respectively. Hyperinsulinism was suspected, and an exaggerated glucose response was detected in a glucagon test. Blood glucose monitoring indicated episodes of fasting hypoglycemia and postprandial hyperglycemia. Diazoxide of 10 mg/kg/day was initiated in 3 doses for hyperinsulinemic hypoglycemia, which resolved without new episodes of postprandial hyperglycemia. The patient deceased at the age of 17 months due to cardiorespiratory failure in the course of severe pneumonia complicated with pulmonary hypertension and hypertrophic cardiomyopathy. Several genetic syndromes including CS are associated with endocrinologic manifestations including abnormal glucose homeostasis. Although the frequency and underlying mechanisms leading to hyperinsulinemic hypoglycemia are yet unknown, hypoglycemia in CS responds well to diazoxide.

Costello Syndrome and Umbilical Ligament Rhabdomyosarcoma in Two Pediatric Patients: Case Reports and Review of the Literature

Costello syndrome is caused by heterozygous de novo missense mutations in the protooncogene HRAS with tumor predisposition, especially rhabdomyosarcoma. We here report two pediatric patients with Costello syndrome and umbilical ligament rhabdomyosarcoma. A review of the literature published in English in MEDLINE from January 1971 to June 2016 using the search terms “Costello syndrome” and “rhabdomyosarcoma” was performed, including two new cases that we describe. Twenty-six patients with Costello syndrome and rhabdomyosarcoma were recorded with mean age of diagnosis of 2 years and 8 months. The most common tumor location was the abdomen/pelvis, including four out of ten of those in the umbilical ligament. The most common histological subtype was embryonal rhabdomyosarcoma. Overall survival was 43%. A total of 17 rhabdomyosarcomas in pediatric patients arising in the umbilical ligament were recorded with mean age of diagnosis of 3 years and 4 months. Overall survival was 69%. Costello syndrome is a poorly known disorder in pediatric oncology but their predisposition to malignancies implies the need for a new perspective on early diagnosis and aggressive medical and surgical treatment.

Costello syndrome and hyperinsulinemic hypoglycemia

Costello syndrome is characterized by mental retardation, loose skin, coarse facies, skeletal abnormalities, cardiovascular abnormalities (congenital heart defects, cardiomyopathy, rhythm disturbances), and predisposition to neoplasia. Endocrine abnormalities including growth hormone deficiency, adrenal insufficiency, glucose intolerance, parathyroid adenoma with hyperprolactinemia and hypoglycemia have been described. Hypoglycemia has been documented due to growth hormone and cortisol deficiency. We report on two patients with Costello syndrome and persistent hyperinsulinemic hypoglycemia and review the endocrine manifestations of Costello syndrome. Both patients required diazoxide therapy to stop the unregulated insulin secretion and maintain normoglycemia. The mechanism of persistent hyperinsulinism in patients with Costello syndrome is unclear.

Behavioral and temperamental features of children with Costello syndrome

Costello syndrome (CS) is a rare genetic condition due to germline mutations in HRAS proto-oncogene and characterized by increased birth weight, postnatal growth retardation, distinctive facial appearance, typical medical problems (including feeding problems in the neonatal period), cutaneous anomalies, and developmental delay. Outgoing personality has often been noted in case reports, but few studies have focused specifically on the behavioral aspects of CS. A preliminary survey described irritability in younger patients with improvement between age 2 and 4, but a standardized psychometric tool was not used. A second study using the Child Behavior Checklist (CBCL) showed relatively high (albeit subclinical) levels of internalizing problems. These descriptive investigations lacked a control group. We describe a comparative survey to evaluate the behavioral and temperamental features of children with CS. We conducted a cross-sectional assessment using the CBCL and the Emotionality, Activity, Shyness, Sociability (EAS) temperament questionnaire to evaluate behavior and temperament in 11 CS children (2 years 5 months to 9 years) comparing them to 33 gender- and age-matched children without disability. The results suggest that the high levels of internalizing problems found before age 4 in CS patients might decrease with age. They also point to possible "hyperemotionality." Further studies using a larger sample size and IQ-matched control groups are needed to more accurately characterize individuals with this rare syndrome.