ESPE Abstracts

Introduction: Neurofibromatosis type 1 (NF1) is an autosomal dominant condition, caused by genetic mutation of NF1 gene in chromosome 17q11.2, with a worldwide incidence of approximately 1 in 3000 people. It is caused by de novo mutation, in about 50%. This is a multisystemic disease, presenting with café-au-lait spots, axillary freckling, skeletal dysplasia and neural crest tumors (benign neurofibromas usually). Autoimmune disease associated with NF1 can be seen, but diabetes mellitus is rarely described in correlation to NF1. Diabetes mellitus type 1 (T1D) is considered the most common chronic metabolic disease diagnosed in children and adolescents. The purpose of this report is to describe a rare case of a boy with coexisting T1D and NF1.

Case description: A 11-year-old boy was admitted to the hospital presenting polydipsia and polyuria for the last week. From his medical history he was under treatment for hypothyreodism since the age of 4. On physical examination, he was haemodynamically stable, while his laboratory tests revealed a blood glucose level of 478 mg/dl (26.6mmol/L), a glycated haemoglobin level of 12% and traces of ketone bodies, with normal liver and kidney function. Urinalysis revealed glucosuria (3+) and ketonuria (4+), acidosis was detected on blood gases analysis (pH=7.19); c-peptide was 0.6ng/ml, tyrosine phosphatase autoantibodies and antibodies to glutamic acid decarboxylase were positive. The rest of his antibodies, as well as thyroid and celiac antibodies were negative. After insulin treatment, normoglycemia was maintenained and his course was uncomplicated. Later he continued his therapy with insuline pump. About one year later, the café-au-lait spots he already had got bigger in diameter (1-6cm) and many new spots appeared (>30) on his abdomen, neck and chest. The diagnosis of Neurofibromatosis type 1 was set since a heterozygous NF1 pathogenic variant was analyzed on genetic sequencing. On furhter investigation, no nodules were found on eye examination, cranial magnetic resonance imaging (MRI) did not reveal any tumors, while an abdominal MRI was performed to rule out somatostatinoma.

Conclusion: Neurofibromatosis type 1 is a genetic condition, with few reports associating it with autoimmune diseases. Diabetes mellitus is rarely seen in patients with NF1, since few cases have been documented, mostly affecting male patients. All the clinicians treating children with NF1 should be open-minded to presenting symptoms of T1D, since an association seems more likely rather than a coincidence, as the number of reports keep increasing