Case 1 -

The Pathology of Decomposition Gregory G. Davis Associate Professor, Forensic Division, Department of Pathology University of Alabama at Birmingham

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When death occurs, the body begins undergoing a combination of autolysis, putrefaction, and depredation by scavengers as it returns to the dust from which it came. Decomposing remains no longer retain the subtle cytologic detail desired for diagnosis in surgical pathology, but careful examination of even skeletal remains often reveals pathological changes sufficient to make a diagnosis of the cause of death. Decomposition Decomposition begins with autolysis and proceeds to putrefaction at some point, depending on the circumstances surrounding death and the environment surrounding the body. Autolysis (fresh) — Autolysis is a minor component of decay commonly seen in hospital autopsies. Autolysis accounts for the softening of the pancreas and adrenal glands familiar from hospital autopsies. Autolysis does not contribute to the next phase of decomposition, in which bacteria begin the process of decay known as putrefaction. Putrefaction — the stage of decomposition in which the body stinks of decay until all soft tissues are gone and only bones remain. Putrefaction occurs when the endogenous intestinal flora begin to spread through the body from the gut. Exogenous bacteria and insects such as maggots begin to colonize the body, primarily through the orifices, but most of the bloating caused by gas production is a result of endogenous bacteria. The onset of putrefaction depends upon the condition of the decedent at the time of death. For example, a patient who is septic at the time of death can begin to putrefy within minutes, particularly in a hot room in summer. In contrast, in a case of a stillborn infant who is wrapped and discarded in trash, putrefaction will be greatly slowed because the fetal gut contains no endogenous bacteria. Times associated with decomposition thus vary widely. As a guide, for the body of an adult left indoors at room temperature and with 50% relative humidity, the timing for putrefaction is as follows: Bloated stage (ends with expulsion of gases through orifices) • Skin slip — epidermolysis, skin slough, begins roughly 24 hours post mortem. • Marbling — roughly 36 hours post mortem, bacteria grow in blood within veins of body • Bloating — roughly 48 hours post mortem; body swells and fills with gases from bacteria • Discoloration — roughly 48-72 hours; skin may turn green or black Active decay — begins when gases from bloating are expelled through orifices, anywhere from 3 days to several weeks depending on temperature; major tissue breakdown by carrion insects and bacteria Dry/skeletal stage — as quick as 2 weeks in the summer in the humid south, as long as months or years if body is buried in snow or if body preserved by special changes described below. Animal activity — may be on land or sea, by wild animals or by pets As mentioned above, a body sometimes undergoes changes which preserve it. Cold preserves, of course, but other special environments, such as peat bogs in the British Isles, can also preserve remains. Two preserving changes seen in North America are mummification and adipocere. Mummification — drying of body, usually develops in warm, dry climates; skin is preserved but internal organs often are not. This finding would be more common in the deserts of the American Southwest. Adipocere — waxy change of fat, usually develops in high humidity or in water; bacterial enzymes of Clostridia (whether from intestines or environment) convert unsaturated fatty acids to saturated fatty acids. Tissue becomes greyish white with a soft, greasy consistency of clay. Adipocere tends to occur in water, whether fresh or salt, so it tends to occur along the coasts or in rivers. Identification of Remains Regardless of the state of decomposition, the charge to a forensic pathologist remains — identify the remains and determine the cause and manner of death. Identification of unknown remains is most easily accomplished by fingerprint comparison. In the absence of fingerprints there are other means of establishing identification, but in that case identification will depend upon a combination of clues and comparison of antemortem and postmortem records of the decedent. Clues include • Visual identification by relatives or friends • Location of body (in home, for example) • Serology/DNA • Identification cards in pocket • Tattoos • Distinctive feature (ring, necklace, dog tag) Scientific identification can be established by comparison of antemortem and postmortem • Fingerprints • Dental records • Radiographs of bony structures • DNA Note that identification by either dental records, radiographs, or DNA comparison require that the investigators have some inkling of who the decedent is, and thus clues are an essential first step in trying to establish identification of remains. Pathological Diagnosis in Setting of Decomposition It is impossible to render a diagnosis such as mild cervical dysplasia on a body that has entered the putrefactive stage of decomposition. The good news is that mild cervical dysplasia will not be the cause of death in a case. Things that do cause death, such as bullets and knives, tend to leave some mark on bony structures. Even strangulation can cause bony injuries detectable despite decomposition. Accidents such as car wrecks leave bony fractures and the physical evidence of the wrecked car. In cases of suicide by hanging the noose will still be evident, possibly with bony injury. Even natural diseases can be detected in putrefying remains. Scar tissue is relatively resistant to decomposition, so extensive myocardial scar and hepatic cirrhosis will both be detectable grossly and microscopically. The persistence of crystals makes it possible to detect talc granulomas in sections of the lungs or oxalate crystals in glomeruli from ethylene glycol consumption. References DiMaio VJM, DiMaio DJ. Forensic Pathology, 2nd ed. New York: Elsevier, 2001. Spitz WU. Medicolegal Investigation of Death, 3rd ed. Springfield, IL: Charles C. Thomas, 1993.