Case Report: Aggressive Tibial Pseudarthrosis as Primary Symptom in Infant with Neurofibromatosis

Abstract

Neurofibromatosis (NF1) is a rare genetic neurologic disorder with over 30 distinct clinical manifestations, the top 3 of which include cafe-au-lait spotting, benign tumors and abnormal freckling. Pseudarthrosis (PA), also known as a \"false joint,\" is a rare subset of NF1 symptomology, characterized by bone fractures and nonunion caused by severe bowing of long bones. To date, it is invariably reported as secondary to NF1, commonly at 24 months of age. Here we describe a 4-month old infant who presented with PA as primary symptom, and in absence of an NF1 first-degree relative. Initial manifestation was guarding of the leg and increased irritability upon palpation of the knee, subsequent to light playful jostling. Physician examination revealed gross anterolateral bowing of the left leg. Radiography confirmed tibia-fibula bowing and pathologic transverse fracture at tibia diaphysis, characteristic of PA. Cafe-au-lait spots developed at 6 months subsequent to PA, but with number and size well below the National Institutes of Health criteria for NF1 diagnosis. At 14 months, exome sequencing established definitive NF1 diagnosis. Treatment involved PA takedown surgery. Although healing was seen after 2 months, complications emerged by 6 months. This case suggests that for primary PA without clear etiology, first-contact and consulting physicians should pay careful attention and be vigilant to timing of clinical onset and severity. Early, severe primary PA warrants accelerated NF1 exome sequencing, suggesting expansion of existing federal guidelines may be necessary to improve detection and prognosis of this rare, debilitating but readily managed condition.\n\nFinancial DisclosureThe authors have no financial relationships relevant to this article to disclose\n\nConflict of InterestThe authors have no conflicts of interest to disclose\n\nClinical Trial RegistrationNA