Forensic Pathology Flashcards
cause of death
disease or injury that initiated the lethal chain of events
o May precede death by seconds or years
o Intermediate illnesses of conditions may connect current fatal condition to initiating condition
o Can stand alone on death certificate
Not: cardiac arrest, respiratory arrest, renal failure, asystole, etc
mechanism of death
nonspecific etiology; broad differential; cannot stand alone on a death certificate
o Cardiac arrest, hypoxia, etc
manner of death
how/circumstances – natural, accident, suicide, homicide, undetermined
rigor mortis
-lactic acid builds up while cells try to stay alive –> this stiffens the muscles
marbling
decomposition that occurs initially in the vasculature
abrasion
scraping and removal of superficial skin; contact with rough surface, by sliding or pressure
o Scrape (linear), Brush burn/Road Rash (frictional force of rubbing against a rough surface over large area)
o pattern reflects object
o readily form thin scab
contusion
area of bleeding (hemorrhage) into the skin or soft tissue as a result of rupture of blood vessels due to blunt force injury or pressure (BRUISE)
o site of contusion isn’t necessarily the point of impact (baseball bat, hand examples)
hematoma
o focal collection of blood
coup and contre-coup
coup injury is on side of impact and contrecoup is on the opposite side of primary impact (brain moves and hits opposite side of skull)
bruising coloration
red/blue/purple/black can occur…
anytime but often are early
bruising coloration
a bruise with yellow….
is atleast 18 hours old
but the converse is not true
laceration
tearing (not a cut or incision) of the skin or tissue due to stretching, crushing, shearing or avulsing by blunt force injury
o Can have abrasion and/or contusions around edges; rarely patterned
o Soft tissue bridging is the hallmark
o NOT a cut or a stab
fracture
lacerations of bone caused by BFI, that occur when the quantity of force overcomes the strength of bone
o Fatal fractures = skull or C-spine
o Long bones fractures are rarely fatal
Fat embolism syndrome
atlanto-occipital dislocation
dens (axis/C2) is horizontally fractured from C1 and occipital condyles of skull base –> severs respiratory centers in the medulla oblongata
2 processes of post mortem decomposition
autolysis and putrefaction
autolysis
aseptic dissolution of organs by intracellular enzymes
**organs with enzymes (pancreas) autolyze faster than those without (ex: kidney)
putrefaction
tissue breakdown by bacterial action gas formation and bloated abdomen, green discoloration, marbling, skin slippage, degloving of hands, brain liquefaction and loss of hair/nails
marbling in decomposition
due to reaction of hgb and hydrogen sulfide that occurs along the blood vessels resulting in green-purple discoloration of skin
green discoloration in decomposition
due to colon bacteria denaturing hemoglobin with hydrogen sulfide to produce green biliverdin
stabs/punctures
o Depth > length
o Wound edges are sharp and straight, NO tissue bridging and no margin abrasions
o May have extensive internal bleeding with minimal external blood loss
o Single edged weapon wound has 1 blunted margin and 1 V shaped margin
o Double edged weapon 2 V shaped margins
o stab wounds with an L or Y shape indicates twisting of weapon or movement of victim
o “Defense wounds” – palms/back of hands, non-fatal, protective position
chop wounds
o Caused by heavy sharp objects dramatic, may have fine abrasion and contusion at margin
o Associated with a wedged cut into underlying bone
incision
o Sharp edge drawn over tissue; width > depth
o Suicide usually has multiple, superficial groupings; “hesitation marks”
o NO tissue bridging, NO marginal abrasions
contact vs immediate range of fire
Contact – muzzle touches body; essentially all the leaves the gun enters the body
Can be hard, loose, near, angled or partial
Immediate – has stippling (tattooing); bits of gunpowder causing abrasions
Hard to cause stippling on palms and soles
asphyxia
systemic or cerebral hypoxia
sign of asphyxia
and how it happens?
conjunctival petechiae
petechiae
d/t increased venous pressure and bursting capillaries
choking presents with
swollen epiglottis
death by hanging is due to
vessel occlusion, not airway obstruction
ionizing vs nonionizing radiation
nonionizing are microwaves, UV waves etc
ionizing is BAD
ionizing radiation can cause these chronic sequelae
fibrosis, mutagenesis, carcinogenesis, and teratogenesis
immediately after exposure to ionizing radiation, you can see
vascular dilation
later changes you see with ionizing radiation are
endothelial cell swelling, vacuolization, necrosis, and thrombosis or vessel rupture
least sensitive tissue to radiation is
adult brain
most sensitive tissue to radiation is
rapidly diving and proliferating; bone marrow, spleen, LNs, (blood forming tissues), reproductive organs, skin, bone, teeth, and muscle
Changes that occur with ionizing radiation
skin dyspigmentation, atrophy, pulmonary interstitial fibrosis, LN fibrosis, and GI fibrosis; followed by scarring, adhesions, keloid formation, and sterility
- ACUTE CHANGES structure changes in chromosomes, nuclear swelling, condensation, and chromatin clumping, and apoptosis
- DNA DAMAGE = Nuclear morphology changes giant cells, nuclear pleomorphism, and binuclear changes AND cytoplasmic changes like swelling, mito distortion, and plasma membrane breakage
anthrax is caused by
what does it look like
• bacillus anthracis large boxcar shaped gram + rods in chains
classic anthrax case
- Case: postal worker presenting with fever, myalgia, malaise, fatigue, retrosternal pain and nonproductive cough
- Papules/vesicles on skin –> characteristic black eschar
classic anthrax cxr
• CXR shows widened mediastinum due to hemorrhagic mediastinitis
how is anthrax acquired?
• Acquired by contact with spores on infected animals or animal products
3 anthrax syndromes
• 3 major syndromes = inhalational (pulmonary), cutaneous, and GI
anthrax toxin
a 3 protein exotoxin secreted by bacteria, made of PA (protective antigen cell binding protein) = B subunit, and A subunit made of EF and LF (edema factor and lethal factor)
A subunit causes edema and cell death!
staph aureus is
• Gram + cocci in clusters
MRSA VRSA MSSA
• MRSA and VRSA are very resistant staph; MSSA = methicillin sensitive (non resistant)
staph aureus effects
- Affects skin and soft tissue of kids and adults; commonly causes osteomyelitis and pneumonia associated with empyema
- Presents with focal destructiveness, puss and abscess formation
staph aureus causes what in diabetics?
infective endocarditis
staph epidermidis
much less virulent than staph aureus and plays a major role in colonizing indwelling medical devices leading to bacteremia (form biofilms); NICU issue
with a staph aureus infection, what is elevated in WBC
neutrophils
SSSS
(staphylococcal scalded skin syndrome) –
thin walled vessels and desquamation (spares mucous membranes) caused by epidermolytic exotoxins (exfoliatin) A and B which are proteases –>released by staph aureus and cause detachment within the epidermal layer by breaking apart desmosomes
