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

Abstract

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.

Keywords: bone growth; case report; class d hfi; cranial pathology; hfi; hyperostosis; hyperostosis frontalis interna; postmenopausal woman.

Figure 1. Hemisected head (right side). Hyperostotic nodules (white arrows) causing frontal lobe compression (green arrows) with the involvement of the SSS and dura mater (white arrows). SS shows no invasion (purple arrow).

SSS, superior sagittal sinus; SS, straight sinus

Figure 2. Severe HFI case. Hemisected skull (right side) showing frontal (F), parietal (P), temporal (T), and occipital (O) bones.

HFI, hyperostosis frontalis interna

Figure 3. Nodular formation (purple arrowheads). Dura mater and SSS (red arrows) are overgrown and obliterated by the nodular formation.

SSS, superior sagittal sinus

Figure 4. Left hemisphere of the brain with ossification of the falx cerebri dura mater (red arrows).

Figure 5. Left hemisphere of the brain. Deep frontal lobe compression (black arrows) and Broca's region (red arrow).

Figure 6. Hemisected skull (left side). Hyperostostic expansion (black arrows) within frontal and temporal bones and 1.5 cm nodular formation (yellow arrow) superior to Broca's area.

Figure 7. Right hemisphere of the brain with frontal lobe compression (white arrows).

Figure 8. Hemisected skull (right side). Hyperostotic expansion (black arrows) within frontal and temporal bones with 5x4 cm triangular-shaped nodular formation (purple arrows). Black arrows show the perimeter of the hyperostosis process.

Figure 9. Cranial fossa overview.

Illustration of the AF, MF, and PF, with the PF largely spared. Key bones include the frontal bone (F), parietal bone (P), and SB. The lesser wing (yellow arrow) and greater wing (green arrow) of the sphenoid bone are highlighted. Cranial nerves shown include facial (CNVII), vestibulocochlear (CNVIII), glossopharyngeal (CNIX), vagus (CNX), accessory (CNXI), and hypoglossal (CNXII). Black arrows indicate the petrous bone. SB, sphenoid bone; AF, anterior cranial fossa; MF, middle cranial fossa; PF, posterior cranial fossa

Figure 10. Skull of a 90-year-old Caucasian female with mild HFI, showing sparing of the midline (white arrow) and nodular formation on the inner surface of the frontal bone bilaterally (purple arrows).

HFI, hyperostosis frontalis interna