Diagnosis of fictitious disorder by proxy in a sibling by administration of anti-vitamin K in an 8-year-old child.

Fictitious disorder by proxy (FDP) is characterized by an adult, often a parent, alleging or fabricating symptoms in a child to induce repeated diagnostic tests or treatments. This form of abuse is particularly serious and difficult to diagnose. Worldwide, it is estimated that 0.5 to 1.2 per 100,000 children are abused in this way every year. We report the case of FDP in an 8-year-old child who presented with coagulation disorders secondary to the unknowing administration of Acenocoumarin. His parents had requested seven medical consultations over a six-month period. The parents systematically reported a coagulation pathology (factor VII deficiency), prompting further investigations and treatment. Biological tests showed deficiencies of vitamin K-dependent coagulation factors, raising suspicion of vitamin K antagonists (VKA) use. Toxicological tests revealed the presence of Acenocoumarin in the child's blood three times, at levels of 0.15 mg/L; 0.06 mg/L and 0.43 mg/L. The biological abnormalities corrected spontaneously after the child was hospitalized. A family investigation led to the diagnosis of medical child abuse in the child's older sister, who presented bleeding. The severity and recurrence of this syndrome correlated with the role that caregivers play in this type of abuse deserves our full attention to prevent and manage it as effectively as possible.