What is Forensic Dermatology?
Forensic dermatology is the study of the skin, hair, and nails to discover a particular cause or mechanism of harm. This can give valuable insight into the medicolegal autopsy, especially when the death is violent, inexplicable, suspicious, or unexpected.
What are the normal changes to skin after death?
A skin examination is very crucial for determining the time of death, which may be determined within the first 48 hours after death.
Algor mortis, or bodily cooling, is one of the early changes observed and may be validated by measuring the body’s skin temperature. It is used to calculate the exact time of death.
Following death, several dermatological results are typical and distinguishable from severe injuries:
• Livor mortis
• Cutis anserine
• Decomposition of Body
Postmortem stiffness or rigidity of the body caused by ATP exhaustion and lactic acid buildup; in a dead body, glycogen resources are rapidly exhausted, prohibiting energy-dependent sarcomere contraction breaking. It is the third stage of death.
Livor mortis, also known as hypostasis, is a red-blue-purple discoloration that appears in the skin of dependent parts of the body after death. Because blood remains a fluid after death, the position of livor mortis can be a valuable hint in determining if the corpse was moved after death.
The optimal time to see livor mortis is six hours after death, and it is usually missing in places of mechanical compression on the body, such as contact points in clothes.
The colour and appearance of livor mortis can help to identify the reason or process of death:
• Cherry Red: Carbon monoxide intoxication, hypothermia, cyanide toxicity, or an artefact of mortuary refrigeration.
• Brown: methemoglobinemia, either primary or secondary.
• Yellow Colour: Phosphorus poisoning.
• Reduced lividity: Large amount of blood loss.
• Ventral lividity with anterior neck blanching: might be a sign of positional asphyxia.
Goose bumps are a transient local alteration in the skin that occurs as a result of the erection of small muscles in response to cold, fear, or excitement. A trigger, like as cold or fear, sets off a series of actions that leads to this skin alteration. It is an early sign of rigour mortis.
Decomposition of the body
The corpse decomposes naturally as a result of increased bacterial activity and the release of cellular enzymes after death. Green discoloration of the abdomen area above the right caecum appears 24 to 36 hours after death due to rapid intestinal breakdown. The colour is the result of microorganisms in the gut breaking down haemoglobin.
Another characteristic of postmortem skin breakdown is ‘marbling’ throughout the trunk and limbs, which is produced by the spread of germs through the venous system.
The body develops widespread swelling and bloating from increased gas production by bacteria from 60 to 72 hours postmortem. Blisters appear after 3 to 5 days, along with skin and hair deterioration. Hair and nails separate from the body after 3 to 4 weeks.
Within one week after death, normal postmortem tissue changes include localised dermal-epidermal separation (a break between the two layers of the skin), eccrine (sweat) duct necrosis, and dermal degeneration.
In forensic dermatology, what kinds of damage patterns do you see?
Identifying self-inflicted, accidental, or deliberately inflicted non-accidental injuries requires a thorough examination of skin findings.
The shape of the penetrating weapon and the force applied to the body can be determined by the appearance of the wound. Cutaneous injuries can be divided into three groups:
• Blunt injuries ( Abrasions, contusions, and lacerations),
• Sharp Injuries (Incisions, stabs, and chop injuries),
• Non-Kinetic Injuries (Chemical, thermal, or electrical traumas).
The following are examples of certain dermatological damage patterns:
• Gunshot wounds
• Cigarette burns: circular lesions with a central depression and rolled edges
• Asphyxia (suffocation): face edoema, cyanosis (blue discoloration), and conjunctival haemorrhage
• Bite marks: round or semi-circular, with bruises around each tooth mark.
Hair and nail samples frequently reveal information about what the subject may have consumed or been exposed to. Hair can be checked to see if it has been dyed or bleached. Toxicology and drug testing can also be done on hair and nails. The DNA of the attacker can be extracted from the victim’s fingernails.
What types of injuries may a dermatologist see?
Loop marks, caused by ropes, cords, or belts, are a common sign of abuse. Bruising, bite marks, fingerprint marks, abrasions from ligatures, and petechiae (small bruises) from asphyxia can all be signs of abuse.