The examination of cranial fractures constitutes a wide-ranging and multifaceted topic within the disciplines of forensic pathology and anthropology. The correct assessment of fracture lines in the skull could be crucial to assess causes and manners of death. Furthermore, discerning the temporal sequence of multiple traumatic events that result in fracturing of a solitary cranium poses an essential yet convoluted endeavor [14,15,16,17,18]. In this context, macroscopic analysis may rely on the Puppe’s rule, as outlined previously. On the basis of a sort of exception to the presumed irrefutability of Puppe’s rule on skull fractures [1,2,3,4,5,6,7], it was shown that in an ‘unexpected’ way, skull fractures were able to pass through existing holes such as holes from previous craniotomies, the margins of which are thus largely remodeled [13]. This phenomenon was attributed to the transmission of forces facilitated by bone remodeling, resulting in fracture deformation. As a result of the previous study and on the basis of the existing literature, it was postulated that the existence of a recent burr hole with non-remodeled edges would disrupt fracture line continuity. Until then, it had never been discussed how a skull fracture behaves when it encounters a craniotomy hole. Instead, the present case provides a significant observation: cranial fractures can indeed pass through recent craniotomy burr holes, with energy transmission deforming the hole and continuing along the margins to the opposite side. This aspect of the behaviour of skull fractures in the presence of craniotomy holes has therefore only been described once before, but it is very important to emphasise that this can be observed with both recent and old burr holes and is a fundamental concept of differential diagnosis, especially when the patient’s clinical history and previous performance of possible neurosurgical operations are unknown. All this leads to the hypothesis that the specific behavior of the fracture is due to the integrity of the hole and not to its remodeling. Consequently, fractures originating from the exit hole, or from a second impact in the case of blunt force, would be interrupted at the margins of the initial entry hole (or the hole given by the first impact), since the margins of the latter are no longer “intact”, in the sense of no longer being in 360-degree continuity due to the prior development of fractures. Nevertheless, it is important to note that in cases involving penetrating injuries from small-caliber projectiles or sharp objects, the occurrence of a bone defect (hole) does not result in any additional fracture [16, 19,20,21]. In such instances, therefore, a craniotomy hole, given the regularity of its margins, can macroscopically resemble a gunshot entry wound (for example, a gunshot entry wound from small-calibre bullet).

In these cases, it must therefore be taken into account that fractures originating from a second impact could cross the hole of the first impact and thus resemble entrance hole fractures. In fact, looking at the fracture lines shown in the figures and assuming that that is an entry gunshot wound, one might mistakenly think that those fractures were caused by the effects of a direct impact.

This should definitely be pointed out and taken into account: a differential diagnosis between fractures starting at the site of trauma or fractures reaching it from a secondary site of trauma. Such a crucial issue has never been described in the literature, but it is something that must be taken into account in the complex evaluation of the origin and course of skull fractures when assessing the sequence of the injuries.