Psychotic major depressive disorder and rapid eye movement sleep behavior disorder cooccurring with a pineal cyst: a case report with neuroimaging insights in a 15-year-old female.

BACKGROUND: Pineal cysts are generally incidental findings on neuroimaging, yet recent evidence has suggested potential associations with circadian rhythm disruption, mood disorders, and sleep dysfunction. This report aims to describe a rare case in an adolescent to explore the potential association between pineal gland abnormalities and circadian dysregulation in the pathophysiology of mood and sleep disturbances. CASE PRESENTATION: We describe a 15-year-old female with a three-year history of depressive symptoms, auditory and visual hallucinations, persecutory delusions, and recurrent self-harm, culminating in multiple suicide attempts. On admission, brain magnetic resonance imaging (MRI) revealed a 7-mm pineal cyst. During hospitalization, polysomnography confirmed rapid eye movement sleep behavior disorder (RBD). Initial treatment with escitalopram, olanzapine, lithium, tandospirone, and lorazepam was complicated by the emergence of RBD, prompting medication adjustments to aripiprazole, clonazepam, and valproate, while escitalopram was continued as the primary antidepressant to minimize RBD-related risks. This change, combined with ten sessions of modified electroconvulsive therapy and supportive psychotherapy, led to significant improvements in mood, psychotic symptoms, suicidality, and sleep continuity. The coexistence of psychotic major depressive disorder, RBD, and a pineal cyst in an adolescent is rare and raises important questions regarding the association between pineal pathology and circadian regulation in patients with psychiatric and sleep disorders. CONCLUSIONS: This case highlights the value of structural neuroimaging in adolescents with psychotic major depressive disorder and underscores the importance of individualized, multimodal treatment planning. Further research is warranted to clarify the clinical significance of pineal abnormalities and their association with mood and sleep disorders.