Abstract Background Malignant ectomesenchymomas (MEMs) are exceptionally rare neoplasms, characterized by their dual composition of mesenchymal and neural components, arising from pluripotent neural crest cells. Case description We describe the case of a 22-year-old female who presented frontal and occipital headaches. MRI revealed a left frontal intra-axial lesion with cystic and hemorrhagic components. Based on imaging findings, a definitive preoperative diagnosis could not be established. Following craniotomy, pathology indicated a high-grade neoplasm with fusocellular and pleomorphic features, high mitotic activity, and reactive gliosis. Immunohistochemistry showed positivity for synaptophysin, desmin, and myogenin, with a Ki-67 index of 60%, supporting a diagnosis of malignant ectomesenchymoma. Next generation sequencing revealed low microsatellite instability and significant TP53 mutations. The patient received intensity-modulated radiotherapy and adjuvant chemotherapy with the ICE protocol. The long-term follow-up is still in progress. Conclusions Despite their initial description in 1975, these tumors remain poorly understood, with limited cases reported, particularly in intracranial locations. This report aims to expand the existing knowledge of MEMs and emphasize the importance of timely diagnosis and comprehensive oncologic care.
Uchima-Vera et al. (Mon,) studied this question.