Histotopography of haemorrhagic infiltration in the hanging cutaneous furrow: Where to look for haemorrhagic infiltration in hanging

Abstract

The forensic evidence of hanging is based on the autopsy demonstration of the traces left by the noose or the ligature on the neck, as well as on the histological assessment of the hanging mark vitality. However, the specific topography of haemorrhagic infiltration in the context of the cervical damaged tissues involved in hanging is not known. We carried out an extensive microscopic examination to identify if haemorrhagic infiltration in hanging appeared in specific topographic locations that could have been considered as elective. From 102 victims of suicidal hanging, a skin fragment was sampled from the maximum compression area of the sulcus, including the skin portions immediately above and below it. The sampling was also extended to collect the subcutaneous adipose tissue and part of the striated muscle. A standard histological examination was performed on all the samples, and hematoxylin and Eosin, Weigert’s resorcin-fuchsin and Goldner’s Masson trichrome staining were performed. In all the cases assessed, the microscopic examination allowed the detection of haemorrhagic infiltration mainly in the deepest areas under the sulcus and especially in the deep dermis and at the transition point between the dermis and the subcutaneous adipose tissue, as well as in the context of its supporting connective tissue. Such areas could therefore be considered as regions in which the presence of haemorrhagic infiltration is more likely to be demonstrated. Accordingly, we recommend performing sampling similar to ours and focusing the search for haemorrhagic infiltration as suggested.

Keywords

Hanging cutaneous furrow haemorrhagic infiltration forensic pathology legal medicine

Introduction

From the perspective of forensic pathology, hanging is the suspension of a person by a noose or ligature around the neck. Usually, the rope is tied to a fixed support in a higher position than the head, and the force applied to the neck is derived from the gravitational drag of the weight of the body. This event causes the gradual tightening of the noose with lethal consequences.¹ Based on the position of the knot, if present, two different types of hanging can be distinguished: typical and atypical.² In the first case, the knot is located on the posterior region of the neck, while in the second, it is positioned in other cervical regions.¹ Even if the suspension of a person is not complete, a fatal outcome can still occur, since the weight of the upper part of the body leaning into the noose is enough to cause death.¹ In the medico-legal diagnosis of hanging, the analysis of the cutaneous furrow and its features is of primary and crucial importance.³ It is usually single and located directly under the chin anteriorly, rising at the sides or back of the neck. Moreover, it is typically deepest at the side diametrically opposite to the suspension point where the maximum load bearing occurs, and there is a segment of skin free from the mark where the cord rises towards the knot. The skin usually appears abraded, brownish and dried to a parchment-like consistency.¹ However, if the noose was applied for a short time⁴ or if it was characterised by softness and width,⁵ the cutaneous furrow may also be superficial and not very evident or even totally absent. Given these critical issues,⁶ the macroscopic examination alone may not be conclusive and can mislead the forensic pathologist.⁴ Also, the finding of hyoid bone and thyroid cartilage fractures should be carefully assessed, as their association with suicidal hanging is a debated topic, having been variably reported in the literature.⁷ Furthermore, even if present, they may not be straightforward to detect macroscopically.⁸ The sulcus may be studied in greater detail through different approaches: histochemical,⁹ immunohistochemical^10,11 and ultramicroscopic.¹² But it is the histological examination that is still considered the gold standard¹ to demonstrate the typical findings of hanging, such as the fragmentation and compression of cervical cutaneous and subcutaneous tissues, as well as the presence of extravascular haemorrhagic infiltration.^4,5 The latter is universally considered a sign of tissue vitality at the time of compressive action on the neck, and therefore it is of the utmost importance in the forensic field.¹ However, the area in which to look for haemorrhagic infiltration in a hanging cutaneous furrow is still a debated topic, and knowledge of its specific topography remains unknown.

In this preliminary study, we addressed this issue by histologically analysing 102 hanging cutaneous furrows. The aims were to evaluate the possible existence of an elective site of haemorrhagic infiltration and, if found, to circumscribe an area of skin on which forensic pathologists may focus their investigations.

Methods

In this study, we enrolled 102 victims who had died by suicide as a result of hanging between 2017 and 2020. All were in a good state of preservation and were subjected to a forensic autopsy at the Institute of Legal Medicine of Milan, Italy. We excluded bodies in an advanced state of decomposition, cases in which accidental hanging occurred and victims who were in drug therapy with any medications that could have interacted with coagulation or blood circulation. We collected data that could in any way have influenced the hanging cutaneous furrow, such as the weight and height of the victims, as well as the type of noose or ligature used. Moreover, during the external examination of the bodies, we took notes on the macroscopic appearance of all the cutaneous furrows, such as position, colour, consistency, width and depth.

In all cases at autopsy, first we opened the skull, removing of the brain to decongest and decompress the cervical veins. Subsequently, a 2 cm×5 cm skin fragment was sampled from the maximum compression area of each sulcus (region B), including the skin portions immediately above (region A, marked with a black dot) and below it (region C, marked with a black triangle; Figure 1). To be able to assess all the soft tissues potentially involved in the hanging lesion, we also cut along the entire length of the skin fragment to sample the subcutaneous adipose tissue and part of the striated muscle.

Figure 1.

Macroscopic view of a hanging cutaneous furrow with detail of the sampled skin fragment. It includes the maximum compression area (region B), alongside the skin portions immediately above (region A) and below it (region C).

Each cutaneous fragment was fixed in 10% buffered formalin for 48 hours and then processed with post-fixative histological techniques consisting of dehydration in an increasing ethanol ladder, diaphanisation in xylene substitute and embedding in high fusion point paraffin (60°C). From each paraffin block, three slices 2 μ thick were cut out, and each of them was stained with different techniques: hematoxylin and eosin (H&E), Weigert’s resorcin-fuchsin (WRF) and Goldner’s Masson trichrome staining. We applied the WRF technique, as it is specific for elastin, and it is useful to demonstrate the compression of elastic fibres. On the other hand, we applied Goldner’s Masson trichrome staining, as it is specific for connective and muscular tissue, and it is also useful to highlight the morphology of red blood cells. All the obtained 306 histological slides were observed by a Leica DMR optical microscope, and the most significant images were acquired with a Leica DC300F digital camera. In the histological results, by the term ‘compression’, we meant the finding of thinned, pressed and stretched cells or connective fibres.

Results

Epidemiological results about the victims

The enrolled 102 victims were mainly of white European ethnic background (95 cases), and only a minority were Asian (five cases) or black African (two cases). Grouping by sex, there was greater involvement of males (83 cases) than of females (19 cases), with a 4:1 ratio. Dividing all cases into decades, we observed that there were four victims aged between 14 and 20 years, 12 victims aged between 21 and 30 years, 24 victims aged between 31 and 40 years, 22 victims aged between 41 and 50 years and between 51 and 60 years, 10 victims aged between 61 and 70 years and four victims aged between 71 and 80 years and between 81 and 90 years. The average weight of the victims was 70 kg (minimum 35 kg; maximum 117 kg), and the average height was 168 cm (minimum 153 cm; maximum 195 cm).

Devices involved and type of hanging

The devices used by the victims to hang themselves included: ropes of almost similar thickness in 53 (52%) cases, belts in 28 (27%) cases, electrical cable in 10 (10%) cases, household linen in five (5%) cases, personal linen in four (4%) cases and metal wires in just two (2%) cases. The suspension was found to be complete in 73 (71.5%) cases, with total lifting of the body from the ground, and incomplete in the remaining 29 (28.5%) cases. Among the cases of complete suspension, typical hanging was observed in 42 (57.5%) cases and atypical hanging in the remaining 31 (42.5%) cases. In the latter cases, the knot was located on the right side of the neck in 17 (55%) cases and on the left side in 14 (45%) cases. On the other hand, among the cases of incomplete suspension, typical hanging was observed in 22 (76%) cases and atypical hanging in the remaining seven (24%) cases. In the latter cases, the knot was located on the right side of the neck in four (57%) cases and on the left side in three (43%) cases.

Macroscopic features of the cutaneous furrows

In all cases, the cutaneous furrows were located directly under the chin anteriorly, that is, in the supra-laryngeal area of the neck. They appeared brownish in 60% of the cases and whitish in the remaining 40%. In most cases, the damaged skin was abraded and dried to a parchment-like consistency. In only three cases, the cutaneous furrows were characterised by serous blisters and narrow reddish strips. Their average width was 0.8 cm (minimum 0.4 cm; maximum 4.0 cm), while their average depth was 0.5 cm (minimum 0.2 cm; maximum 1.5 cm).

Histological examination

In all cases, the skin areas above and below the sulcus did not show any significant pathological findings (Figure 2(a) and (c)). The main histological alterations were detected in correspondence and deep to the cutaneous furrows (Figure 2(b)). All findings concerning regions A, B and C will be described proceeding from the skin surface to its deepest regions.

Figure 2.

Microscopic views of the three skin areas sampled for each case. (a) Region above the cutaneous furrow, with preserved histoarchitecture of the skin, as well as undamaged stratum corneum, epithelial cells and adnexa that appear well adherent to the dermis (H&E, 100×). (b) Region of the sulcus with pronounced compression and dehydration of the most superficial skin layers. The dermal connective tissue has evident lacerations in its deepest area, and some foci of undamaged connective tissue can be only detected at the transition point with the subcutaneous adipose tissue (TM, 100×). (c) Region below the cutaneous furrow, with preserved histoarchitecture of the skin and normal subepithelial and dermal elastic component (WRF, 400×). H&E: hematoxylin and eosin staining; TM: Goldner’s Masson trichrome staining; WRF: Weigert’s resorcin-fuchsin staining.

Region A, above the cutaneous furrow (marked with a black dot)

The epithelium was free of lesions. A dilatation and congestion of the superficial and deep vessels of the dermis, as well as well-preserved elastic fibres with tendency to aggregation, were observed. In no case were foci of inflammatory or haemorrhagic infiltration detected.

Region B, the cutaneous furrow

In the epithelium, fragmentation and focal absence of the stratum corneum, as well as its compression, were observed. The epithelial cells were partly thickened enough to be hardly recognisable. In the transition area between the epithelium and the dermis, vesicles of irregular shape and volume were detected, in the absence of any detachment from the dermis. In no case were foci of haemorrhagic infiltration observed. In the dermis, a pronounced full-thickness compression was observed, along with fragmented elastic fibres and different-degree damage of the skin adnexa. On the whole, the sweat glands were more damaged than the sebaceous ones. In the deepest areas of the dermis, several foci of haemorrhagic infiltration were often detected. In the subcutaneous adipose tissue, several foci of haemorrhagic infiltration of variable entity (Figure 3) were documented in all the cases enrolled in this study. From a histotopographic point of view, such foci were located at the transition point between the dermis and the subcutaneous adipose tissue and, focally, in the context of its supporting connective tissue. The extravascular red cells forming such infiltrates appeared well defined and with a preserved shape (Figure 3(a) and (b)), dissociating the connective tissue fibres, the connective tissue bundles of the deep dermis and the lobules of the subcutaneous adipose tissue (Figure 3(c)–(f)). In a few cases, some alterations were documented in the extravascular red blood cells, consisting of a swollen, rounded appearance and a pale central portion, with a tendency to aggregate (Figure 3(g) and (h)). A dilatation and congestion of the blood vessels were observed (Figure 3(i)–(l)). In no case were foci of inflammatory infiltration detected. In striated muscle tissue, a variable degree of compression was observed in the absence of haemorrhagic infiltration.

Figure 3.

Microscopic view (H&E, 50×) of the hanging mark with several foci of haemorrhagic infiltration in the deepest cutaneous layers, dissociating the connective tissue fibres. (a) and (b) Microscopic view of the deepest tissues under the hanging mark, where extravascular red blood cells can be observed (TM 50× on the left). They are better highlighted in the picture at higher magnification (TM 100× on the right). (c)–(f) Microscopic views of the deepest tissues under the hanging mark, with extensive foci of haemorrhagic infiltration involving not only the deep dermis but also the subcutaneous adipose tissue, dissociating the adipose lobules (TM 100× (c) and (e)). Such findings are better highlighted in the pictures at higher magnification (TM 200× (d), 400× (f)) on the right. (g), (h), (i) and (j) Microscopic views of the deepest tissues under the hanging mark, with evidence of foci of haemorrhagic infiltration and red blood cells affected by some alterations. (g) Recent haemorrhagic infiltration in the deep dermis (H&E, 200×). It is highlighted at a higher magnification in (h) (H&E, 400×), in which the red blood cells show a rounded appearance and a pale central portion. (i) Extensive haemorrhagic infiltration of the subcutaneous tissue, with evidence of a dilatated and congested blood vessel located in the deep dermis (TM 100×). (j) Detail at a higher magnification of the haemorrhagic infiltration dissociating the connective fibres of the deep dermis.

Region C, the area below the cutaneous furrow (marked with a black triangle)

The epithelium was free of lesions, and both superficial and deep vessels of the dermis were clearly visible. They looked large, dilated and filled with blood. The elastic fibres showed compression and distance from each other, but overall, they appeared quite preserved. The connective tissue and skin appendages were tense. In four (4%) cases, a few foci of haemorrhagic infiltration were detected but only in the deep dermis. In no case were foci of inflammatory infiltration observed. The above-mentioned results are summarised in Table 1.

Table 1.

Main histological findings observed in this study, with a particular focus on the presence or absence of foci of haemorrhagic infiltration.

Sampling area	Skin layers	Histological findings
Region A (the area above the sulcus)		Epithelium free of lesions; no foci of haemorrhagic infiltration
Region B (the sulcus)	Epithelium	Fragmentation and compression; no foci of haemorrhagic infiltration
	Transition area between the epithelium and dermis	Vesicles of irregular shape; no foci of haemorrhagic infiltration
	Dermis	Full-thickness compression; in all the cases, evidence of several foci of haemorrhagic infiltration in the deepest areas
	Subcutaneous adipose tissue	In all the cases, evidence of several foci of haemorrhagic infiltration
	Striated muscle tissue	Variable degree compression; no foci of haemorrhagic infiltration
Region C (the area below the sulcus)		Epithelium free of lesions; in four cases, evidence of foci of haemorrhagic infiltration in the deep dermis

Discussion

Hanging is one of the most common suicide modalities³ in the world.¹³ It can be performed as a single act or in combination with other means.^14–20 It can also be the consequence of an accidental event, particularly in children, as the tragic conclusion of play activities.²¹ Less commonly, accidental hanging occurs in adults, in which generally it is associated with alcoholic intoxication²² or is the result of auto-erotic sexual or masochistic practices.²³ Although very rare, there are also hangings with murderous purposes^24,25 whose realisation presupposes the presence of at least two attackers or disproportion of strength between the aggressor and the victim, or even that the victim is in a drug- or alcohol-related state of unconsciousness or reduced consciousness. Finally, it may happen that the body of a victim who died as a result of a criminal action, usually a murder,¹⁰ is subsequently hanged (i.e. suspension of a body)²⁴ to simulate a suicide,²⁶ with the consequence that the true manner of death may remain undiscovered or even excluded.⁵ Regardless of the manner of death, in all cases of hanging, the autopsy plays a crucial role, with the external cadaveric examination and the assessment of the cutaneous furrow aimed at demonstrating the tissue vital reaction. In particular, only through histological analysis of the hanging mark is it possible to detect foci of haemorrhagic infiltration in the involved soft tissues, therefore demonstrating that the hanging occurred when the subject was still alive. However, to the best of our knowledge, the specific histotopographic location of haemorrhagic infiltration in the cervical tissues involved in hanging has not yet been clarified.

To define whether it was possible to identify specific areas in which such haemorrhagic infiltration is more likely to be detected, we sampled skin fragments from the maximum compression area of 102 hanging cutaneous furrows, including the skin portions immediately above and below them. The microscopic study on these samples was performed with H&E, WRF, which is specific for elastic fibres, and Goldner’s Masson trichrome staining, which is specific for both connective tissue and red blood cells. The latter was therefore performed to assess all the potential areas for localisation of haemorrhagic infiltration better. H&E highlighted the typical alterations of a hanging mark. The study of elastic fibres carried out with WRF staining showed an always-present compression of the elastic component of the dermis under the sulcus. On the contrary, the dermal areas of the skin portions above and below the hanging mark appeared to be undamaged. Goldner’s Masson trichrome staining proved to be very sensitive and specific for optimal evaluation of the vascular component and the quantity of intra- and extravascular red blood cells. Indeed, it allowed the identification of foci of haemorrhagic infiltration in the deep dermis and at the transition point between the dermis and the subcutaneous adipose tissue, as well as in the context of its supporting connective tissue.

In the cases enrolled in this study, haemorrhagic infiltration in hanging cutaneous furrows presented the following distributions. In all cases, the epithelial layer of all the three sampled regions (regions A, B and C) did not present extravascular red blood cells, consistent with the absence of a capillary network and the solidity of the basement membrane. The other tissue layers, that is, the dermis, the hypodermis and the muscular component of regions A and C, were negative. Exceptions were four cases in which poor micro-foci of haemorrhagic infiltration were detected in the deep dermis of the skin portion below the cutaneous furrow (region C). On the other hand, in the deepest areas under the cutaneous furrow (region B), that is, in the deep dermis and at the transition point between the dermis and the subcutaneous adipose tissue, as well as in the context of its supporting connective tissue, several foci of haemorrhagic infiltration were successfully observed in all the cases. They appeared widespread, with well-preserved extravascular red cells dissociating the adjacent structures, that is, with the typical features of vital reaction. These findings were similarly observed regardless of the weight, height and typology of the ligature used by the victims.

To date, the forensic literature does not clarify the topographic location of haemorrhagic infiltration in the hanging mark, nor does it guide the quantification of the same to be considered vital.² We therefore hypothesised that the almost exclusive topographic location of haemorrhagic infiltration in the deepest areas under the cutaneous furrow (region B) may be attributed to two different consequential factors. In the first place, the sulcus represents the area where the ligature expresses its maximum traumatic force with marked skin stretching, massive rupture of deep capillaries and extravasation of red blood cells. Second, the constant compressive effect of the noose around the neck may already be enough not only not to allow the superficialisation of haemorrhagic infiltration but also to prevent it from spreading to the areas above and below the hanging mark. In the latter, the presence of poor micro-foci of haemorrhagic infiltration in four of our cases could be attributed to a twofold mechanism: the rupture of capillaries from blood stasis and descent of the red blood cells from the deepest areas under the cutaneous furrow (region B) by force of gravity.

In this study, we carried out a microscopic evaluation of a large number of hanging cutaneous furrows to try to identify an elective site of haemorrhagic infiltration. Its presence is universally considered to indicate a soft-tissue vital reaction following a lesion, and therefore it represents one of the most pivotal research topics in the forensic field. As far as hanging is concerned, to date, specific topographic locations of where to search for haemorrhagic infiltration have not yet been demonstrated, and for this reason, further investigations are needed to address such an aspect fully. In all the cases in our study, the presence of haemorrhagic infiltration was demonstrated in the deepest tissues under the hanging mark, in particular in the deep dermis and at the transition point between the dermis and subcutaneous adipose tissue, as well as in the context of its supporting connective tissue. Such areas could therefore be considered as sites in which the presence of haemorrhagic infiltration is more likely to be demonstrated. Future studies are necessary, and they could also investigate a possible correlation between such results and fractures of the hyoid bone or thyroid cartilage to improve the diagnostics of cervical lesions in cases of suicidal hanging.

In conclusion, we consider these results to be extremely significant, and therefore, for the forensic assessment of the vital reaction of hanging cutaneous furrows, we strongly recommend performing a sampling similar to ours and focusing the search for haemorrhagic infiltration as suggested.

Footnotes

Declaration of conflicting interests

All the authors declared no potential conflicts of interest with respect to the research, authorship and/or publication of this article.

Funding

The authors received no financial support for the research, authorship and/or publication of this article.

ORCID iD

Riccardo Zoja

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