RESUMO
Medulloepithelioma is a rare and highly malignant tumor of infancy and early childhood, and classified as a primitive neuroectodermal tumor. Considering that most cases occur in the central nervous system, development in atypical sites associated with secondary comorbidities, such as peritoneal carcinomatosis, becomes an extremely rare association due to its high morbimortality. This study reports a rare case of peripheral medulloepithelioma with peritoneal carcinomatosis in an 11-year-old boy, with a 4-year history of intestinal constipation alternated with fecal incontinence, taken to the emergency room due to increasing abdominal pain and urinary retention. This report aims to contribute to a better understanding of this rare pathology, as well as assist in the establishment of early diagnosis and treatment.