Hyperostosis fronto-parietalis - radiology mimic of metastasis: A case report

Abstract

Hyperostosis frontalis interna (HFI) is a benign entity manifested by bony overgrowth in the frontal endocranial surface. It is most commonly reported incidentally among postmenopausal elderly women. Tracer uptake appearances of HFI can vary on planar bone scans, enabling it to be easily confounded with bone metastases. We report a case of HFI in a 69-year-old postmenopausal female with treated left breast cancer detected on bone scintigraphy, with subsequent confirmation by computed tomography. Our case highlights the importance of having awareness of HFI and its key pattern findings to avoid mistaking it for pathology, and to recognise the use of computed tomography and hybrid fusion imaging techniques as reliable diagnostic tools for HFI.

Keywords: Bone metastasis; Computed tomography; Hyperostosis frontalis interna; Hyperostosis fronto-parietalis.

Fig. 1

99mTc-methylene diphosphonate planar bone scan reveal asymmetrical abnormal increased tracer uptake involving the bilateral fronto-parietal regions of the skull. Tracer uptake in the remaining skeleton were within normal limits.

Fig. 2

Sagittal, axial and coronal CT images of the skull show irregular, nodular thickening of the frontal bone inner table extending to involve the parietal bones, with sparing of the midline and outer calvarial surface.