Autopsy & forensics

• Blunt object: an object that has a wide, dull or convex surface with rounded edges or corners; does not possess any pointed or sharp edges
• Blunt force injuries: produced by blunt objects due to different possible mechanisms
  • Moving blunt object impacting against a resting body
  • Moving body impacting against a resting blunt object
  • Moving body and a moving blunt object collide
  • Body is trapped between 2 surfaces

• Skin injury consisting of the traumatic removal or detachment of the epidermis due to friction (shearing) or pressure (crushing) mechanisms
• Tangential abrasions: a lateral rubbing mechanism that scrapes off the superficial layers of the skin; epidermal shreds (skin tags) can be present and may suggest the impact's direction, although this phenomenon does not always occur
  • Linear abrasions: caused by a sliding movement of a narrow object on the skin, which results in superficial epidermis denudation; typical examples are fingernail abrasions that can be observed in manual or ligature strangulations (Am J Forensic Med Pathol 1981;2:45, J Clin Forensic Med 2003;10:255)
  • Brush abrasions: caused by the body's frictional movements against a wide, rough surface or object, leading to scraping of the epidermis; usually wider at the starting point and narrower at the end (e.g. "road rash" in traffic accidents) (J Clin Forensic Med 2003;10:255)
• Compression abrasions: direct pressure from a blunt object together with slight rubbing movements produce skin and epidermal crushing
  • Patterned abrasions: these injuries show a distinct pattern that may reflect the shape of the impacting blunt object; frequently observed in tortures (Forensic Sci Int 2018;284:85)
    • Typically occur when the force is applied at or near perpendicular to the skin surface and can be classified as:
      • Impact abrasions: occur when a force is applied suddenly or rapidly and perpendicular to the skin, pushing and crushing it on a body surface
      • Pressure abrasions: occur when there is a slow, prolonged compression of the skin by a blunt object, which results in a dried, parchment-like abrasion (e.g. hanging mark)
  • Nonpatterned abrasions: abrasions that don't resemble the producing object
• Differential diagnosis in abrasions:
  • Antemortem abrasions (with survival interval):
    • Usually dark red or red, covered with a dark scab and showing signs of healing
    • Inflammatory cell infiltration, evidence of hemorrhage or granulation tissue are histologic signs of vitality (Clin Dermatol 2007;25:39)
  • Postmortem abrasions:
    • Several mechanisms can produce abrasions in the postmortem period (autopsy procedures, insect activity, body dragging on a rough surface, etc.)
    • Usually orange-yellow or brown with a parchment appearance (J Forensic Leg Med 2014;26:10, Am J Forensic Med Pathol 2009;30:84)
• Dating of abrasion: despite recent research describing possible morphological features to establish an abrasion's age, it is extremely difficult to reach reliable conclusions based on the morphology of the injury (Am J Forensic Med Pathol 2017;38:167)

• Basilar skull fractures: delayed bruises may follow cranial base fractures but they should not be considered definitive evidence of a specific cranial base fracture
  • Anterior cranial fossa fracture: conjunctival, palpebral or periorbital bruises (raccoon eyes) with or without liquorrhea or bleeding from the nose (J Neurosci Rural Pract 2018;9:370)
  • Middle cranial fossa fracture: bruising visible behind and below the ear at the mastoid process (Battle sign) or bleeding from the ear (StatPearls: Battle Sign [Accessed 8 February 2021])
  • Posterior cranial fossa fracture: Battle sign or pharyngeal bruises / hematomas
• Commotio cordis: cardiac concussion in which a blunt impact to the precordium leads to a cardiac rhythm disorder in the absence of structural heart damage (Leg Med (Tokyo) 2019;38:73, Med Sci Law 2017;57:146)
• Acceleration / deceleration injuries:
  • Typically observed in motor vehicle collisions
  • Rapid deceleration results in differential movements among adjacent structures, resulting in the tearing of visceral organs, ligaments and vascular pedicles
  • Internal organs are also crushed between the anterior abdominal wall and the spine or posterior chest, leading to severe parenchymal lacerations
• Blast injuries (Philos Trans R Soc Lond B Biol Sci 2011;366:144):
  • Typically observed in explosions
  • Following the detonation, a shock wave (blast or pressure wave) propagates radially from the original point, acting as a blunt force when interacting with the body
  • Lungs, middle ear (barotrauma), gastrointestinal tract and bones are the most affected body areas
• Chop lacerations:
  • Injuries that show both blunt and sharp force trauma features
  • Produced by a heavy blunt object with a sharp edge (e.g. cleaver)
  • Typically show abraded and bruised edges with a clean separation of the margins and no tissue bridges
• Resuscitation injuries: cardiopulmonary resuscitation (CPR) or other procedures may result in physical injuries that can be hard to interpret during autopsy (J Forensic Leg Med 2015;33:39)
  • Commonly observed injuries are:
    • Bruises and abrasions on the scalp and face (e.g. use of a mask for resuscitation, intubation attempts, pinching of the nose during mouth to mouth resuscitations, etc.)
    • Bruise and abrasions on the precordial region or the central chest area due to external compressions during cardiopulmonary resuscitation
    • Rib and sternum fractures and soft tissue hemorrhages are commonly associated
    • Laceration of the heart, lungs, pleura and pericardial sac may result from rib fractures
    • Electrical burns from defibrillation, in the form of a rectangular, parchment-like, yellow-orange abrasion on the anterior chest
    • Retinal hemorrhages have been rarely described in children following cardiopulmonary resuscitation (J Forensic Sci 2017;62:107)

Contributed by Lorenzo Gitto, M.D., Robert Stoppacher, M.D., Serenella Serinelli M.D., Ponni Arunkumar, M.D. and Luigi Bonaccorso, M.D.

How are the lesions shown in the image best characterized?

1. Contact dermatitis
2. Electrocution
3. Postmortem insect activity
4. Road rash
5. Third degree thermal burn

D. Road rash. This is an antemortem abrasion typically observed in traffic accidents when the body slides against the rough asphalt, producing injuries with a burnt appearance (also called brush burns). Postmortem abrasion shows a leathery, yellow-brown parchment appearance. Postmortem insect activity (typically ants) usually produces abrasion along the edge of clothing or floor irregularities if the body is in contact with the floor (e.g. edges of cobblestones). Third degree burns are full thickness burns that go through the dermis and affect deeper tissues. Electrical burn typically consists of a depressed leathery area of tissue necrosis, occasionally with blistering. Contact dermatitis is a red, itchy rash caused by direct contact with a specific item or substance and typically resembles the allergen's shape.

Comment Here

Reference: Blunt force injuries

What weapon / mechanism most likely caused the injury depicted by the 2 red arrows?

1. Hammer: striking the skin at a shallow angle
2. Metal pipe tube: 2 bruises due to 2 distinct hits
3. Metal pipe tube: single injury due to one hit in the center
4. Postmortem artifact: lividity
5. Shoe: kicking

C. Metal pipe tube: single injury due to one hit in the center. This is a typical tram track bruise due to cylindrical or rod-like objects (e.g. metal pipe). When the weapon strikes the body, the skin is compressed and there is no damage to the underlying vessels but the blood accumulates laterally to the point of impact due to the rupture of blood vessels on either side of the impacting object. The resulting bruise appears as a pale, undamaged central area lined on either side by 2 parallel lines of bruising. Kicking usually results in patterned abrasions / bruises resembling the morphology of the shoe sole. Lividity is usually bilateral and symmetrical, uniform in color, shows pallor on digital pressure and is preferentially located in the body's dependent portions. Hammer injuries are usually focal and resemble the shape of the hammer’s head.

Comment Here

Reference: Blunt force injuries

What is the best description for the injury depicted in the yellow circle in this victim of a traffic accident?

1. Avulsion laceration
2. Chopping injury
3. Necrotizing fasciitis
4. Stab wound injury
5. Tissue procurement artifact

A. Avulsion laceration. The finding is consistent with a typical avulsion laceration, a severe form of laceration in which the soft tissues, musculature or bone are torn away from the normal points of attachment. The tissues are often completely detached and these injuries may bleed profusely. A stab wound is a penetrating injury to the skin that results from a sharp or similar pointed object. Chopping wounds are injuries produced by heavy blunt objects that also possess a sharp edge that shows both sharp force (cuts) and blunt force (abrasion and contusion). Necrotizing fasciitis is a rare bacterial infection that spreads quickly in the body and results in diffuse necrosis of fascia, skin and subcutaneous tissue.

Comment Here

Reference: Blunt force injuries