ObjectivesMunchausen syndrome by proxy is defined by the production of factitious disorders on an individual by a close relative, generating a medical nomadism and more or less invasive somatic treatments. The reported cases of victims range from the perinatal period to adulthood. The existence of cases in adolescents raises the question of the victim's participation, conscious or unconscious, in Munchausen syndrome by proxy. The aim of this study was to investigate the type of adolescent involvement in this syndrome. Patients and methodsWe collected a series of height cases hospitalized in the Children and Adolescents Psychiatry Department of the Pitié Salpêtrière Hospital, from 1994 to 2022. These patients were hospitalized in a context of complex clinical expressions for which the diagnosis of Munchausen syndrome by proxy was a possibility. We studied the different psychopathological aspects of these eight cases from the medical records (hospitalization reports, patient interviews, psychological and psychomotor assessments). ResultsWe described 8 cases of hospitalized children,aged between 9 and 17 years. Their functional symptoms were psychiatric and sometimes somatic. The additional benefits were, for the majority of them, to receive parental attention, with an improvement noted in all patients during the separation from the relative. We studied the patient's participation in the different cases described, and the awareness level of their own participation. DiscussionThese different clinical observations enable us to outline a systemic dimension with a system composed of the perpetrator, the “victim” patient and the doctor suggesting a participation of each member in the system. The psychopathological arguments found are the improvement at the separation from the relative, systemic dysfunctions, a family organization around the relationship of two members, most often between the child and his mother without a third person and more particularly without a paternal figure, fostering an exclusive mother-child dyadic interaction. All of the benefits secondary to the production of the disorders are mainly aimed at maintaining a “fusional” relationship with the parent, based on somatic or psychiatric symptoms. In these complex cases, we question the participation of the child, seeking to meet the expectations of his parent who sees him as a chronic patient, in this pathology initially induced by a family member. In view of the systemic arguments, we propose the term “shared” rather than “by proxy” Munchausen syndrome in cases of active or passive and partially conscious participation of the adolescent in the subterfuge. ConclusionThis series has thus led us to favor a systemic approach especially in the older adolescents and to introduce the concept of shared Munchausen syndrome. We collected cases of Munchausen syndrome “by proxy”, especially in younger patients, cases of “shared” Munchausen syndrome and cases of patients who self-inflict lesions with a conscious and active participation in the Munchausen syndrome suggesting an evolution towards a “classic” Munchausen syndrome. We can assume that the different syndromes of Munchausen “by proxy”, “shared” or “classic” present themselves as a continuum according to age and psychic maturity.