Hyperostosis frontalis interna as an age-related phenomenon - Differences between males and females and possible use in identification

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

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.

Comparative Analysis of Femoral Macro- and Micromorphology in Males and Females With and Without Hyperostosis Frontalis Interna: A Cross-Sectional Cadaveric Study

We hypothesized that subjects with hyperostosis frontalis interna (HFI), which represents local, endocranial thickening of the frontal bone, would express extra-calvarial manifestations of this condition. Therefore, we compared femoral bone mineral density, geometry, and microarchitecture of males and females with HFI to those without this condition as well as between males and females with HFI. The sample was taken from human donor cadavers, 38 males (19 with and 19 without HFI) and 34 females (17 with and 17 without HFI) that were age-matched within the same sex. The specimens of femoral bones were scanned using microcomputed tomography and dual-energy X-ray absorptiometry (DXA). Parameters of hip structure analysis (HSA) were calculated from data derived from DXA scans. Females with HFI had increased cortical bone volume fraction and their cortical bone was less porous compared to females without HFI. Males with HFI showed microarchitectural differences only with the trabecular bone. They had increased bone volume fraction and decreased trabecular separation compared to males without HFI, although with borderline significance. These microarchitectural changes did not have significant impact on femoral geometry and bone mineral density. The same, still unknown etiological factor behind HFI might be inducing changes at the level of bone microarchitecture at a remote skeletal site (femoral bone), in both sexes. These alterations still do not have the magnitude to induce obvious, straightforward overall increase of bone mineral density measured by DXA. HFI could be a systemic phenomenon that affects both males and females in a similar manner.

Micro-computed Tomography Study of Frontal Bones in Males and Females with Hyperostosis Frontalis Interna

Hyperostosis frontalis interna (HFI) represents irregular thickening of the endocranial surface of the frontal bone, mostly seen in postmenopausal females. The microarchitecture of this condition is poorly studied. The aim of this cross-sectional autopsy study was to investigate and compare microarchitectural structure of the frontal bone affected with HFI in both sexes and to test whether HFI severity could be distinguished at the microarchitectural level. The sample was taken from human donor cadavers, 19 males (61 ± 15 years old) and 17 females (75 ± 15 years old). After classification of HFI severity (type A, B, C or D), samples of the frontal bone were taken and scanned using micro-computed tomography. Bone volume fraction was higher and total porosity lower only in the outer table of males with HFI, compared to females with HFI. Mean total sample thickness differed only between males with HFI type A and D. Bone microarchitecture between males and females with corresponding HFI types (e.g., male with type A versus female with type A) differed only in HFI type C regarding the fractal dimension of diploe. The degree of anisotropy differed between HFI subtypes in males, but the post hoc analysis revealed no significant differences between individual groups. Other microarchitectural parameters did not differ among males with different HFI subtypes, as well in females, in any part of the frontal bone. There is no difference in microarchitectural structure of the frontal bone between males and females with HFI, in general aspect and within corresponding HFI subtypes. HFI severity could not be distinguished at the microarchitectural level, neither in males nor in females.

Skull Abnormalities in Cadavers in the Gross Anatomy Lab

Background

The skull encompasses and houses one of the most important organs in the body—the brain—and like all tissues in the body, it is comprised of living cells that are constantly remodeling as this maintains the strength and homeostasis of the bone. In the present study, abnormal bone growth patterns were observed and the possible causes of said findings were investigated in multiple cadaver skulls dissected during head and neck anatomy courses at Detroit Mercy Dental over the past year. There are many factors, both intrinsic and extrinsic, with differences in stimulation to the skull resulting in skull abnormalities. Materials and Methods. For this study, skull abnormalities were examined from 65 formalin-embalmed cadaver heads, obtained from the Gross Anatomy Laboratory at the University of Detroit Mercy School of Dentistry between the years 2016 and 2019. We have recorded the age, sex, and previous chief medical issues of all lab specimens used in the study. Skulls were later evaluated for possible indications of bone disease such as hypertosis frontalis interna (HFI) or Paget's disease.

Results

Among the sixty-five specimens provided to the Detroit Mercy Dental cadaver lab, 19 specimens (29%) were found to present with irregular, undulating, thickening of the frontal bone internal surface. The findings located on the skulls closely resembled the gross anatomic appearance of HFI or Paget's disease; however, a conclusive diagnosis of these skull abnormalities cannot be made without a pathologist biopsy and radiological examination. Twelve of the nineteen specimens that displayed possible bone disease, approximating 63% prevalence, were females; their ages ranged from 68 to 95 years old. Thus, seven of the nineteen specimens exhibiting features of skull abnormalities, approximating 36% prevalence, were males with ages ranging from 70 to 103 years old. In addition, five of these nineteen specimens collected (26% prevalence) had been diagnosed with neurological disorders, including Alzheimer's, dementia, depression, and Parkinson's disease. In the current study, the proportion of specimens exhibiting skull abnormalities was higher compared to the overall prevalence observed in previous studies.

Conclusion

Possible causes of observed anatomical abnormalities in the skull of cadavers of a gross anatomy laboratory were investigated, and it was determined that hypertosis frontalis interna (HFI) may contribute to such abnormalities. This is a condition that affects bone growth in the frontal skull. Our numbers of skull abnormalities were higher than previous studies and might be due to the fact that HFI was predominately present as an incidental finding during imaging of postmenopausal females or observed postmortem in cadavers. In addition, Paget's disease or hormonal imbalances could also result in similar features, and thus cannot be ruled out as a plausible cause. Paget's disease causes the bone to deposit at a faster rate than normal, which will result in thick and brittle bone. Studies that will involve further examination of new cadavers for the presence of HFI is needed, either using biopsy specimens and/or radiological examination to explore possible causes for the abnormal bone growth in the frontal bone.

Finding of Hyperostosis Frontalis Interna During the Autopsy Procedure: Forensic Issues

Hyperostosis frontalis interna is a common phenomenon, which may have been overrated in its significance in the past, and may, currently be underrated in its significance. We present three cases of hyperostosis frontalis interna found during medicolegal autopsies and discuss their forensic considerations. The patients were all middle-aged women with metabolic and endocrine manifestations and psychiatric ailments; thickening of the inner table of the frontal bone of the skull was found during each autopsy. We describe the relationship between hyperostosis frontalis interna, metabolic manifestations, and neuropsychiatric symptoms as part of Morgagni-Stewart-Morel syndrome. There is still considerable disagreement in the scientific community as to whether this syndrome is a clinical entity. Nonetheless, awareness of Morgagni-Stewart-Morel syndrome can be of help in understanding the circumstances surrounding death. In some other cases, hyperostosis frontalis interna could be used by forensic pathologists as criteria for sexing and aging a skeleton.