A 13-year-old boy was referred to our specialized consultation for EDs. He was born full-term with a birth weight of 3410 g and a length of 50 cm. He had no eating difficulties in early childhood. An agenesis of the two upper lateral incisors was observed. Around the age of 10, the patient began to complain of abdominal pain, which was described as intense, beginning around the umbilical region, and spreading rapidly throughout the abdominal area. The pain was characterized by its severity, with a desire to “cut open his stomach with a knife” due to its distressing intensity. Concomitantly, the patient displayed an escalating food restriction, particularly exacerbated during school time. These dietary symptoms gradually worsened in severity over time. He limited his food intake, out of anxious anticipation and for fear of abdominal pain. Food quantities became increasingly reduced. The patient showed food selectivity, preferring fatty and sweet foods and excluding fruits and vegetables. He was not purging, was not taking medication to control his weight, and was not engaging in physical hyperactivity. The patient did not show any lack of interest in eating or sensory problems. Significant family history among first degree relatives included: agenesis of the upper lateral incisors in the oldest brother, and pulmonary teratoma and desmoid tumor of the rectus muscle in the mother in adulthood. A high-grade glial tumor in the maternal grandfather, pleural cancer in the paternal grandfather, and ovarian cancer in the paternal grandmother were also reported. There were no previous familial cases of EDs nor psychiatric disorders. At the age of 13, the adolescent was referred because of his eating difficulties. During the initial ED specialized consultation, the adolescent’s weight stood at 30 kg for 1.51 m, with a body mass index of 13.0 kg/m² (-3 SD). We observed a loss of 1.5 SD in weight and 1 SD in height compared with the last biometric data (Fig. 1).

Patient growth curves. The arrow represents the time of surgical removal of the tumor, followed by a significant ponderal gain, a resumption of growth and an increasing BMI

The patient did not express a desire for voluntary weight loss, exhibited no preoccupation with body image, and had no fear of gaining weight. The clinical examination was strictly normal with a puberty stage at Tanner 2. The patient did not report symptoms of intracranial hypertension, such as headaches, vomiting, or balance disorders. The patient was alert and oriented. He had no sensory-motor neurological deficits at the time of consultation. Examination of the cranial pairs was unremarkable. Osteotendinous reflexes were normal. There were no walking or balance disorders, no coordination problems and no tightness of the neck. The family only reported a marked change in the adolescent’s handwriting over the past year. The initial blood biology test revealed no abnormalities (Table 1).

Combined with his eating difficulties, the adolescent presented with increasingly severe anxiety, which became more pronounced during the school year. He also had episodes of intense anger whenever he was frustrated. The patient and his family underwent regular psychological assessments. No relevant psychosocial difficulties were identified that might contribute to EDs. He had no other psychiatric symptoms and did not require psychotropic or anxiolytic medication. Given the impact on growth, writing difficulties and intense abdominal pain, a brain MRI was requested. The cerebral MRI revealed a median mixed cystic mass in the posterior fossa, measuring 6 × 5 × 6 cm, causing an upward displacement of the cerebellum and anterior displacement of the medulla oblongata and pons. This mass presented a T1 hyposignal and a T2 hypersignal with several mural nodules in intermediate T2 hypersignal, enhancing after injection. In addition, the pituitary gland was abnormally small, with a radiological image of an empty sella turcica, associated with dilation of the lateral ventricles and the fourth ventricle (Fig. 2).

Pre-operative non-contrast MRI axial Flair and sagittal T1. Arrows represent the cerebellar tumor

The patient was immediately referred to the pediatric neurosurgical department for removal of the tumor as an extreme emergency. The operation was performed without intraoperative complications. Histopathological assessment of the surgical specimen revealed features consistent with a grade 1 ganglioglioma, expressing the BRAF V600E mutation. A post-operative MRI performed the day after the surgery demonstrated residual tumor tissue, partially hemorrhagic (Fig. 3). A few days after neurosurgery, the patient’s eating habits improved impressively. He resumed eating a diet adapted to his age and was no longer afraid of having a stomachache after eating. We continued to follow this patient in our specialized consultation for EDs after the surgical treatment.

Post-operative MRI, axial and sagittal with gadolinium injection. Arrows represent the post-operative tumor residue

One year following neurosurgery, the patient successfully adhered to a diet aligning with age-appropriate nutritional standards, progressively integrating a diverse array of foods without any selectivity. A significant improvement in growth and weight was observed, characterized by a gain of 20.3 kg and 13 cm one year after surgery (Fig. 1). Puberty also progressed to Tanner stage 4. The adolescent no longer reported intense and disabling abdominal pain. His handwriting also improved a few months after surgery. A follow-up brain MRI, conducted one year later, revealed progressive growth of the tumor remnant located in the left cerebellar hemisphere. This remnant measured 41 × 24 mm transversely. The proximity of the tumor to the dentate nucleus ruled out the possibility of further surgery. A decision was made to initiate targeted anti-BRAF therapy, involving a combination of BRAF and MEK inhibitors, with a partial response to this treatment. The improvement in eating habits was constant throughout this period. There were no relapses in dietary difficulties or concerning the patient’s weight growth. The 2-year follow-up showed continued increase in weight, growth and puberty, with a weight of 59 kg for 1m76 (BMI 19). Biological assessment at 2 years revealed a possible incipient thyrotropic deficiency with low TSH level of 0.49 mIU/L (0.5–4.3 mIU/L), slight decrease FT4 level of 12.2 pmol/L (12.6–21 pmol/L) and normal FT3 level of 5,5 pmol/L (3,9 − 7,7 pmol/L), with no disturbance of the other hypothalamic-pituitary axes. The patient and his family have been satisfied and reassured by the collaborative work between our adolescent medicine team and the neurosurgery and oncology departments. Patient has shown excellent adherence and tolerance to anti-BRAF therapy, and regularly visits our specialized adolescent medical center for somatic and endocrinologic follow-up and psychological support. The sequence of medical events is reported in a timeline (Fig. 4).

Clinical events and therapeutic interventions timeline