Although Type III external occipital protuberance (EOP) is a normal variant, its enlargement (hyperostosis) may cause cosmetic discomfort and pain in the occipital region in the supine position or on palpation, even becoming so painful as to require surgical excision; in addition, it is often confused with subcutaneous pseudotumours in the occipital region. Since research on the prevalence of Type III EOP hyperostosis remains limited, the aim of the present study was to determine the prevalence and describe the morphometric characteristics of Type III EOP hyperostosis in a sample of dry craniums from the Colombian population, in order to contribute knowledge of the variability of bone anatomy and its clinical and anthropological implications. One hundred and twenty-six dry craniums of adult individuals were examined. Subsequently, for the Type III external occipital protuberances that presented hyperostosis, their morphometric characteristics were established, such as the vertical diameter of the base (VDB), the transverse diameter of the vertex (TDV), and the major longitudinal diameter (MLD). 2.38% of cases developed EOP Type III hyperostosis, exhibiting two different morphotypes: hook-shaped and pyramidal spinal-shaped. The VDB ranged between 13.21 mm and 18.23 mm, the TDV between 4.18 mm and 6.01 mm, and the MLD between 10.10 mm and 16.59 mm. The morphometric characteristics of EOP have anatomical, clinical, and surgical implications, so these dimensions could be considered in the clinical evaluation of patients with EOP that present cervical pain and occipital headache, avoiding confusion in the diagnosis with subcutaneous pseudotumours in the occipital region.
