31 Forensic Lung Pathology Michael A. Graham Sudden and unexpected natural deaths and nonnatural The cause of death is the disease or injury that begins deaths may result from various pulmonary conditions. the unbroken pathophysiologic sequence leading to Additionally, several nonpulmonary conditions of foren­ death. The disease/injury that causes death at a particular sic significance may be complicated by the development time is often referred to as the immediate cause of death. of respiratory lesions. Certain situations with pulmonary The disease/injury that starts the unbroken chain of pathology are particularly likely to be critically scruti­ medical events culminating in death is referred to as the nized and may form the basis of allegations of medical underlying cause of death. Proper recognition of the latter negligence, other personal injury liability, or wrongful is very important for death certification, epidemiology, death.l public policy, and the proper resolution of criminal justice The forensic evaluation of lethal or nonlethal conditions and civil liability issues. 2 The mechanism of death is the is essentially the same and conceptually differs little from nonspecific pathophysiologic alteration through which a clinician's approach to a patient with a similar condition the cause of death exerts its lethal influence. The manner (Table 31.1). In some cases this diagnostic/investigative of death is a term peculiar to death certification that process is quite broad, whereas in other cases the issues describes how death came about-through natural causes, are of very limited scope and the investigation may be homicide, suicide, or accident.2 The determination of the narrowly focused. The pathologist may playa critical role manner of death is heavily dependent on the investiga­ in these evaluations, not only by addressing the above­ tion of the circumstances surrounding the death or, if noted issues, but also by documenting pertinent findings death is delayed, the illness or injury ultimately respon­ that other experts may rely on in formulating their opin­ sible for death. In some cases the information will not ions; properly recognizing, collecting, preserving, and enable a clear determination to be made, and a classifica­ transmitting physical evidence; and presenting findings tion of undetermined may be warranted. and opinions in appropriate legal forums. The most important determination of the manner of The focus of many forensic evaluations is on establish­ death is to differentiate deaths due to natural conditions ing the cause and manner of death. The elucidation of the from those stemming from some nonnatural manner. Any mechanism of death may also be of importance in some case in which a nonnatural manner is contemplated must cases. In other cases, the cause of disease or injury, timing be referred to the appropriate medicolegal authority, of lesions, establishing the presence or extent of lesions medical or coroner, for review. It is important to remem­ and any response to therapy, evaluating modifying or ber that a "natural" disease may arise in a fashion that contributory factors to death or disability, or correlating merits a nonnatural manner of death (e.g., Yersinia pestis findings with antemortem activity or condition may be at pneumonia acquired as the result of an act of bioterror­ issue. As noted above, the process to arrive at these deter­ ism is homicide). minations has the same components as a clinician's Pulmonary findings may also help resolve other medi­ approach to a patient: assessment of the history, physical colegal issues that may arise in a particular case. The sig­ examination, and ancillary studies. nificance of any particular finding must always be In fatalities, determinations of the cause of death, considered in the context of the issues being addressed. manner of death, and mechanism of death are often The significance of a particular finding can be thought of important. Commonly, there is confusion about the mean­ in medical/physiologic terms (i.e., what effect it has on ings and use of these terms as they apply to medicolegal the person) or in forensic (investigative) terms (i.e., what death investigation and death certification. light it sheds on the nature, age, or cause of a disease/ 1174 31. Forensic Lung Pathology 1175 TABLE 31.1. Death investigation process Examine History Circumstances surrounding, leading Past history Scene Body Ancillary tests Interpret Correlate injury). The medical significance and the investigative sig­ nificance can be mutually exclusive; medically important findings may be of minimal, if any, investigative help, while a medically trivial finding may be the critical datum in resolving an important investigative issue. A variety of pulmonary lesions may be associated with or cause sudden, unexpected death. Although there are a variety of definitions of sudden death, the most com­ monly used refers to death occurring within 1 hour of the onset of symptoms or signs. In addition to being sudden, deaths coming under the jurisdiction of the medicolegal FIGURE 31.1. Acute epiglottitis. Swollen hyperemic epiglottis with focal mucosal necrosis. official, medical examiner/coroner, also are unexpected. These conditions may result from primary natural disease conditions or may arise during the course of or as sequelae to some other underlying disease or injury. epiglottis is often markedly swollen and hyperemic (Fig. 31.1), whereas in adults epiglottitis is characterized by more diffuse supraglottic swelling (Fig. 31.2). Microscopic Sudden Unexpected Death examination demonstrates suppurative inflammation that, in some cases, may be restricted to the deep central Epiglottitis portions of the epiglottis (Fig. 31.3). Acute epiglottitis is characterized by the abrupt onset of a clinical complex often including sore throat, dysphagia, high fever, "hot-potato" voice, drooling, and airway pro­ tective head and neck posturing.3 The disease may prog­ ress very rapidly and cause sudden obstruction of the airway. Death is typically caused by airway obstruction or sepsis. Overall, mortality is less than 5%. Haemophilus influenzae type b (Rib) is responsible for causing most cases in children and adults. In the prevac­ cine era (Rib vaccine was introduced circa 1985 to 1992), Rib was responsible for 75% to 90% of pediatric epiglot­ titis. 3 Currently, 25% to 32% of cases are caused by Rib. A variety of other organisms, including Streptococcus pneumoniae, are currently responsible for a significant number of cases. 3 The clinical features of epiglottitis have remained the same as before the vaccine was available.3 Introduction of the vaccine has also changed the epide­ miology of epiglottitis. There has been a 95% decrease in the incidence of Rib diseases.4 In addition, the average age of patients with epiglottitis has increased? The gross appearance of the inflamed epiglottis differs somewhat between children and adults. In children the FIGURE 31.2. Acute epiglottitis. Diffuse supraglottic swelling. 1176 M.A. Graham FIGURE 31.3. Acute epiglottitis. A. Note lack of exudate on surface. B. Acute necrotizing inflammation in the deep epiglottic tissue. Other Causes of Laryngeal Obstruction most cases represent either fulminant pneumonia or, more commonly, pneumonia in a person who has not Tumors, cysts, and other proliferative lesions obstructing sought medical help until late in its course, if help was the larynx and resulting in sudden unexpected death sought at all. Bacterial and viral pneumonias may present are rare. Among these lesions are laryngeal carcinoma in this fashion. (Fig. 31.4), laryngeal papillomatosis,S inflammatory polyps Occasionally, true sudden, unexpected death may occur (Fig. 31.5), hypopharyngeal lipoma,6 laryngeal cyst/ in an adult as a result of undiagnosed pneumonia. These laryngeal schwannoma,8 and prolapsed esophageal individuals have minor, if any, respiratory symptoms and 9 fibrolipoma. die suddenly while carrying out their usual daily activities. Autopsy typically demonstrates extensive pneumonia, Pneumonia often in a lobar distribution. In my experience, S. pneu­ moniae is the organism most commonly isolated from the Pneumonia is occasionally encountered as a cause of lungs of these individuals, many of whom are chronic unexpected death in adults and in children. Among adults, alcoholics. For example, a man was sitting on his usual bar FIGURE 31.4. Laryngeal obstruction. Squamous cell carcinoma effaces the right hemilarynx. FIGURE 31.5. Laryngeal obstruction. Inflammatory polyps. 31. Forensic Lung Pathology 1177 stool in the neighborhood tavern talking and appearing cally with anti-RSV antibody. There may also be a peri­ normal when he suddenly collapsed to the floor, dead. bronchial, peri bronchiolar, and interstitial infiltrate of The postmortem examination demonstrated acute mononuclear cells and neutrophils (see Chapter 11).18-20 pneumococcal pneumonia due to S. pneumoniae with complete consolidation of the left lung. Asthma Similarly, it is not uncommon to find extensive pneu­ monia in an infant who is found dead with minimal, if any, Asthma is a common disease, affecting 20% of children prior signs or symptoms suggestive of significant anteced­ and 5% of adults.21 Fortunately, the number of deaths ent infection. In cases in which the child displayed ante­ attributable to asthma is relatively low. An increased risk mortem signs of infection, the infection was usually of death has been associated with a variety of epidemio­ thought