Giant Intradiploic Angiolipoma of the skull. Report of the first case with MR and histopathological characteristics reported in the literature and a review

BACKGROUND: Intraosseous Angiolipoma of the skull bone (IOAL) is a very rare bony lesion of the calvarium. This lesion occurs most commonly in the soft, subcutaneous tissue of the trunk. Only a single case of angiolipoma of the skull has been previously reported. The authors report the first case of giant IOAL of the calvarium evaluated by 3D CTS, MRI and full histopathological staining in a young lady treated surgically and with 23 months of follow up. CASE DESCRIPTION: A 41-year-old female was admitted because of a prominent bulging on her right parietal region. Three dimensional CT and CT angiographic reconstruction of the cranium elucidated the geographical pattern of the lesion. MRI revealed a huge intraosseous right frontotemporoparietooccipital expansile lesion, nonhomogeneous but mostly hyperintense, in T1W images. In T2W images, the lesion was nonhomogeneously hyperintense and trabeculated with no perilesional edema. In the FLAIR-images, the lesion was trabeculated and nonhomogeneously hypointense. The lesion was excised totally followed by skull reconstruction and no recurrence after 23 months. CONCLUSION: We hypothesize that the possible pathogenesis of IOAL may be a kind of mutation or dedifferentiation of either a primary intradiploic hemangioma or lipoma changing its growth pattern with possibly more aggressive behavior.