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<b><i>Introduction:</i></b> Melanotic neuroectodermal tumor of infancy (MNTI) is a rare and rapid-growing tumor. However, a neurosurgeon should not overlook this entity when differential diagnosing rapid-growing skull tumor because its histology nature is just benign, and the prognosis is much better than other malignant tumors. <b><i>Case Presentation:</i></b> We reported the case of a 5-month old male presenting with progressive rapid-growing skull tumor which became 10 cm in diameter in only 5 months compared to the normal head circumference at birth. At first, we thought of malignant skull tumor and performed only biopsy to establish diagnosis. But, when the pathology revealed benign MNTI, we performed preoperative tumor embolization and then radical surgery. Good result was observed. <b><i>Discussion:</i></b> Skull MNTI is the second most common location after the maxilla. Even advanced imaging nowadays cannot distinguish MNTI from other malignant tumors definitely. Urgent biopsy is recommended to establish diagnosis of this benign tumor first. Preoperative angiography with tumor embolization is recommended when feasible, followed by craniotomy with radical resection.

This report highlights a rare case of a benign orbital intramuscular lipoma mimicking a malignant tumor with unusual sphenoid wing destruction. A 2-year-old female patient presented with proptosis of the left eye, left temporal fullness, and motility disturbance during abduction. Brain and orbital computed tomography revealed an inhomogeneous enhancing density partially circumscribed mass in the left extraconal space (36.6 × 34.4 × 34.2 mm) with bone erosion of the greater wing of the left sphenoid bone. The clinical and radiologic findings suggested rhabdomyosarcoma. Histopathology revealed diffuse infiltration of mature adipocytes in the striated muscle. An intramuscular lipoma, a rare subtype of benign lipoma, can mimic malignant orbital tumors due to adjacent bone erosion.