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Autopsy Findings in Burns - Third Year Forensic Medicine

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Classification of Burns (Background)

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EXTERNAL EXAMINATION at Autopsy

1. Skin Changes

• Searing burns: Skin is light brown, stiff and leathery in consistency
• Blisters: May be present; importantly, blisters do NOT confirm the victim was alive - they can form postmortem. Even a red (erythematous) rim around blisters or burns does NOT confirm antemortem injury - heat contracts dermal capillaries forcing blood to the periphery, mimicking an inflammatory response
• Skin splitting: In severely burned bodies, skin may split or be completely burned away, exposing underlying muscle
• Charring: Progressive blackening and destruction of tissue; muscle may show rupture from heat
• Leathery consistency: Any unburned skin has a seared, leathery feel

2. Pugilistic Attitude (Boxer's Posture) - KEY EXAM POINT

• Definition: Flexion posture of all four limbs resembling a boxer with hands raised
• Mechanism: Heat causes coagulation and contraction of muscle fibers, leading to flexion of all limbs; upper extremities assume position of a boxer
• Medico-legal significance: The pugilistic attitude is NOT related to whether the individual was alive or dead prior to the fire - it is purely a heat artefact

3. Hair and Skin Surface

• In flash burns: Hair is singed; all exposed surfaces burned uniformly
• In radiant heat burns: Hair initially remains intact; later charring occurs
• In contact burns: Trans-epidermal necrosis at surface temperature ≥70°C in <1 second

4. Exposed Bone

• Burned bone becomes gray-white in color
• Shows a fine superficial network of heat fractures on the cortical surface
• May crumble on handling (calcination)
• The skull is frequently affected: scalp burns away exposing the cranial vault; outer table shows crisscrossing heat fractures; outer table can fragment and become absent
• Face: soft tissue commonly burned away, revealing the skull (partial skeletonization)
• Hands and feet: Often absent in severely burned bodies (fragmented at scene)

5. Extent of Body Surface Burns

• In adults: >40% TBSA burns are considered life-threatening
• In children: >20% TBSA burns are life-threatening

6. Distinguishing Antemortem vs. Postmortem Burns

• On gross examination, it is usually impossible to distinguish acute antemortem from postmortem burns
• Microscopic examination is not helpful unless the victim survived long enough to develop an inflammatory response
• Absence of inflammatory response does NOT necessarily indicate a postmortem burn (heat thrombosis of dermal vessels can prevent inflammatory cell migration even in antemortem burns)

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INTERNAL EXAMINATION at Autopsy

1. Respiratory Tract - Smoke Inhalation

• Soot coating found in: nostrils, mouth, larynx, trachea, and bronchi
• Absence of soot does NOT mean the person was dead before the fire - blood may still show lethal carboxyhemoglobin (COHb) levels

2. Blood and Organs - Carbon Monoxide Poisoning

• Cherry-red coloration of:
  • Livor mortis
  • Muscles
  • Internal organs
  • Blood
• Average COHb in fire deaths: ~57% (range 20-70%+)
• Compare: auto exhaust deaths average ~79% COHb
• Despite the cherry-red color, a blood CO determination is mandatory
• Cherry-red livor can also occur in cold exposure and cyanide poisoning

3. Visceral Changes (Severely Burned Bodies)

• Chest and abdominal walls may be burned away, exposing the viscera
• Internal organs may appear seared or charred
• On cremation sequence studies: by 30 min, internal organs are blackened and shrunken; intestines blackened anteriorly but moist posteriorly

4. Postmortem Epidural Thermal Hematoma - KEY ARTEFACT

• Common artefact in severely burned bodies with head charring
• Formed by heat causing expansion of blood/fluid between dura and inner skull table
• Characteristics:
  • Chocolate brown color
  • Crumbly or honeycomb-like appearance
  • Large and fairly thick (up to 1.5 cm)
  • Typically overlies frontal, parietal, and temporal areas; may extend to occipital area
• Distinguished from antemortem epidural hematoma: antemortem EDH is dark red/gelatinous and conforming; postmortem thermal EDH is brown, crumbly, and honeycomb
• This distinction is medico-legally critical when evaluating for trauma

5. Lungs

• Inhalation of hot dry air up to 350-500°C causes little to no lung injury (upper trachea may show mild injury only) - heat is dissipated before reaching lungs
• Hot steam/moist air causes far more severe lower airway injury
• Inhalation injury causes edema, mucosal ulceration, and later pulmonary complications

6. Causes of Death in Burns (Internal Evidence)

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Key Medico-legal Points for Exam

1. Pugilistic attitude = heat artefact, unrelated to vital reaction
2. Postmortem blisters with red rim can occur - do NOT indicate antemortem burning
3. Postmortem epidural hematoma from fire must NOT be confused with antemortem trauma
4. COHb determination is mandatory even without cherry-red coloration
5. Soot in airways is best evidence of ante-mortem smoke inhalation (person was alive and breathing during fire)
6. Gross examination alone cannot distinguish antemortem from postmortem burns
7. Body parts in protective positions (under another body, on a floor) may be spared from burns

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