Unusual Adolescent Abdominal Tumors Presenting With Neuropsychiatric and Massive Abdominopelvic Manifestations: A Report of Two Cases

Abdominal tumors in adolescence represent a diverse group of pathologies that can present atypically, ranging from neuropsychiatric disturbances to significant abdominal distension. The objective of this study is to report two rare cases that highlight the diagnostic and therapeutic challenges of abdominal tumors in this age group. In the first case, a 12-year-old girl presented with a 10-day history of acute-onset neuropsychiatric symptoms, including hallucinations and cognitive decline, leading to a diagnosis of anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis. Although the initial ultrasound was non-diagnostic, subsequent magnetic resonance imaging (MRI) revealed a 3-cm ovarian dermoid cyst. Prompt surgical resection combined with immunotherapy resulted in rapid neurological improvement, with complete recovery observed within days and sustained at a one-year follow-up. In the second case, a 14-year-old girl exhibited progressive abdominal distension over one month and was found to have a large, predominantly solid pelvic mass. Detailed imaging studies, including computed tomography (CT), delineated a bilobed mass measuring up to 30 cm in maximum dimension. Intraoperative findings confirmed the mass to be an intramural uterine leiomyoma; surgical excision led to the resolution of symptoms and normalization of laboratory parameters (hemoglobin improved from 8.6 g/dL), with no recurrence noted during follow-up. These cases quantitatively underscore that even benign tumors measuring 3 cm and 30 cm, respectively, lead to significant morbidity. Ultimately, our findings emphasize the importance of a high index of suspicion, repeated high-resolution imaging, and a multidisciplinary approach to ensure timely diagnosis and optimal management, thereby contributing to improved clinical strategies in the management of atypical abdominal tumors in adolescents.