title: Skull parosteal lipoma with reactive hyperostosis: a case report.
abstract: A 50-year-old female presented with more than 20-year history of a large subcutaneous mass in the left parieto-occipital portion. Magnetic resonance (MR) imaging revealed the lipomatous mass to show a high signal intensity in both T1- and T2-weighted images. A part of the lipomatous lesion progressed into the underlying hyperostosis and skull. The preoperative diagnosis was skull invasion of a well-differentiated liposarcoma. The tumor was removed completely, including the underlying hyperostosis and skull. Microscopy confirmed a lipoma without any lipoblasts, which was firmly attached to the reactive hyperostosis, and islands of lipoma were involved in the underlying hyperostosis and skull cortex. A pathological diagnosis of parosteal lipoma with reactive hyperostosis was made. Long-term progression of parosteal lipoma may cause to involve the underlying hyperostosis and skull, and led to the diagnosis of invasion of a malignant tumor on MR imaging.
authors.affiliation: Department of Neurosurgery, Kyoto Kujo Hospital.
authors.forename: Mamoru
authors.initials: M
authors.lastname: Murakami
authors.forename: Makoto
authors.initials: M
authors.lastname: Hirai
authors.forename: Takehiko
authors.initials: T
authors.lastname: Sakakibara
authors.forename: Tarumi
authors.initials: T
authors.lastname: Yamaki
authors.forename: Katuyuki
authors.initials: K
authors.lastname: Kusuzaki
mesh_terms: D003937:Diagnosis, Differential; D018450:Disease Progression; D005260:Female; D006258:Head and Neck Neoplasms / Q000150:complications / Q000473:pathology* / Q000601:surgery; D006801:Humans; D015576:Hyperostosis / Q000209:etiology*; D008067:Lipoma / Q000150:complications / Q000473:pathology* / Q000601:surgery; D008279:Magnetic Resonance Imaging; D008875:Middle Aged; D009361:Neoplasm Invasiveness / Q000175:diagnosis; D009777:Occipital Bone / Q000473:pathology*; D010294:Parietal Bone / Q000473:pathology*; D040521:Subcutaneous Tissue; D014057:Tomography, X-Ray Computed