Severe Hyperostosis Frontalis Interna in a 91-Year-Old Female Cadaver: A Case Report.

Hyperostosis frontalis interna (HFI) is characterized by benign thickening of the frontal bone and most commonly affects postmenopausal elderly women. While the exact cause remains unknown, its prevalence is thought to be multifactorial. This case report presents a discovery of extensive HFI during routine dissection of a 91-year-old female cadaver in the Clinical Anatomy Laboratory of Sam Houston State University College of Osteopathic Medicine. The patient's (donor) death was reported as systolic heart failure, and complete bilateral invasion of the frontal and temporal bones, with lesser involvement of the parietal bone, was observed. This condition extended from the crista galli anteriorly to the coronal suture posteriorly and to the sphenoid bone (SB) inferiorly. The greater and lesser wings of the SB were covered by the hyperostotic processes and the foramina (rotundum, ovale, spinosum, and lacerum) bilaterally. The cranial vault demonstrated an irregular surface with numerous nodular, trabeculated, and spiculated bony projections, creating a cobblestone-like appearance, a feature commonly referred to in pathology as bosselated lesions. A mild expansion into the superior sagittal sinus (SSS) and the dura mater was observed, which is uncommon for this condition. Based on postmortem pathology, a suspected diagnosis of advanced type D HFI was made. This report discusses a unique case of HFI that may contribute to a better understanding, classification, evaluation, and treatment of patients affected by this condition.