11-months-old male showed signs of tumefaction in the left frontotemporal region. An ultrasound showed a solid noncalcified neoformation, and a brain CAT scan showed a small solid lesion resulting in erosion of the cranial theca both in the external and internal table. Based on clinical status and tomodensitometric appearance, the diagnosis of suspected eosinophilic granuloma or hystiocytosis X was made, and a surgical curettage of the craniolacunia was recommended in order to comfirm the diagnosis.