ABSTRACT Sclerosing Mesenteritis (SM) is a rare diagnosis, particularly in pediatric patients, and is typically non-fatal when appropriately treated. Although molecular and immunohistochemical alterations have been described, no pathognomonic signature has been identified for this entity. This report presents a case of a seven-year-old boy who suffered sudden cardiorespiratory arrest. Upon autopsy, he was found to have multicentric SM on the upper mesentery, which led to bowel wall thinning and abdominal bleeding with bacterial translocation. We performed comprehensive morphological, immunohistochemical, and molecular analyses. SM is an atypical disorder with diverse clinical manifestations, including a rare but potentially fatal course. Early diagnosis is critical, given its potential severity. To our knowledge, this is the first case report of pediatric mortality linked to SM. Our findings emphasize the importance of increased awareness and early detection of SM in pediatric patients.

Abstract: Central Giant Cell Granuloma is an infrequent bone lesion located mainly in the maxillary bone. The main treatment is surgery with wide margins, so it sometimes causes great morbidity and esthetic alterations. Denosumab, a RANK-ligand inhibitor monoclonal antibody, has been presented as a valid therapeutic alternative in the treatment of these lesions. Objective: to describe the clinical and radiological response after treatment with Denosumab in a patient with unresected giant cell granuloma. Clinical Case: 12-year-old boy who consulted due to a 24-hour maxillary swelling, without other associated symptoms. Examination revealed a tumor in the upper left maxilla with bulging of the ipsilateral gingiva. A CT scan was performed which showed a large expansive intraosseous lesion in the maxillary alveolar ridge. The biopsy of the lesion was compatible with Central Giant Cell Granuloma. Due to the size and location of the lesion, initial treatment with Denosumab, a human monoclonal antibody with action on RANK-ligand, was indicated. After 10 months of treatment, the patient showed a favorable clinical and radiological response, with a size decrease of the lesion and metabolic activity. As an adverse effect, the boy presented mild hypocalcemia, resolved after supplementation with calcium. Conclusion: the use of Denosumab as the first line of treatment in Giant Cell Granu loma may be an adequate therapeutic option in adolescents with lesions that are difficult to resect.

Resumen: Introducción: El granuloma central de células gigantes (GCCG) es una lesión ósea poco frecuente que asienta pre dominantemente en el hueso maxilar. Su principal tratamiento es la cirugía con márgenes amplios, por lo que en ocasiones condiciona gran morbilidad y alteraciones estéticas. Denosumab, un anti cuerpo monoclonal inhibidor de RANK-ligando, se ha presentado como una alternativa terapéutica válida en el tratamiento de estas lesiones. Objetivo: describir la respuesta clínica y radiológica tras tra tamiento con Denosumab en un paciente pediátrico con GCCG no resecado. Caso Clínico: adoles cente de 12 años que consultó por tumefacción maxilar de 24 h de evolución, sin otra clínica asociada. A la exploración constatamos tumoración en región maxilar superior izquierda con abombamiento de encía ipsilateral. Se realizó una tomografía computarizada (TC) en la que se observó una gran le sión intraósea expansiva en borde alveolar maxilar, solicitándose posteriormente biopsia de la lesión con diagnóstico anatomopatológico de GCCG. Debido al tamaño y localización de la lesión se optó por tratamiento inicial con Denosumab. Tras 10 meses de tratamiento el paciente presentó respuesta clínica y radiológica favorable, con disminución del tamaño lesional y la actividad metabólica. Como efecto adverso asoció hipocalcemia leve, resuelta tras suplementación con calcio. Conclusión: el em pleo de Denosumab como primera línea de tratamiento en Granuloma de Células Gigantes puede ser una opción terapéutica adecuada en adolescentes con lesiones difícilmente resecables.