The investigation of possible anaphylactic shock is frustrating for forensic pathologists because the diagnosis is based on exclusion and circumstantial evidence. Morphologically, anaphylaxis is nonspecific, sometimes involving only visceral congestion and other times involving airway obstruction caused by edema and mucous plugging. Upon microscopical examination there is occasionally evidence of edema in the respiratory mucosa, discrete inflammation with eosinophilia, and epithelial desquamation. There has yet to be a proper evaluation of the number of mast cells in different organs and tissues in anaphylactic deaths and, moreover, degranulated mast cells are difficult to identify in postmortem tissues. However, the postmortem diagnosis of anaphylaxis has been made easier by immunological methods that detect and quantify mast cell proteases, particularly tryptase. One noted problem is that sudden anaphylaxis death and death by food anaphylaxis may not lead to elevated tryptase. Additionally, tryptase has been elevated in some cases believed not to be caused by allergy and it has also been found that an artifactual increase in tryptase may be caused by postmortem diffusion from tissues into blood. As such, it is crucially important for the forensic pathologist to have knowledge of the patient’s history and circumstances of death. References