When is pneumonia not pneumonia: a clinicopathologic study of the utility of lung tissue biopsies in determining the suitability of cadaveric tissue for donation.

Healthcare-associated pneumonia (HCAP) represents a major diagnostic challenge because of the relatively low sensitivity and specificity of clinical criteria, radiological findings, and microbiologic culture results. It is often difficult to distinguish between pneumonia, underlying pulmonary disease, or conditions with pulmonary complications; this is compounded by the often-subjective clinical diagnosis of pneumonia. We conducted this study to determine the utility of post-mortem lung biopsies for diagnosing pneumonia in tissue donors diagnosed with pneumonia prior to death. Subjects were deceased patients who had been hospitalized at death and diagnosed with pneumonia. Post-mortem lung biopsies were obtained from the anatomic portion of the cadaveric lung corresponding to chest radiograph abnormalities. Specimens were fixed, stained with hematoxylin and eosin, and read by a single board-certified pathologist. Histological criteria for acute pneumonia included intense neutrophilic infiltration, fibrinous exudates, cellular debris, necrosis, or bacteria in the interstitium and intra-alveolar spaces. Of 143 subjects with a diagnosis of pneumonia at time of death, 14 (9.8 %) had histological evidence consistent with acute pneumonia. The most common histological diagnoses were emphysema (53 %), interstitial fibrosis (40 %), chronic atelectasis (36 %), acute and chronic passive congestion consistent with underlying cardiomyopathy (25 %), fibro-bullous disease (12 %), and acute bronchitis (11 %). HCAP represents a major diagnostic challenge because of the relatively low sensitivity and specificity of clinical criteria, radiological findings, and microbiologic testing. We found that attending physician-diagnosed pneumonia did not correlate with post-mortem pathological diagnosis. We conclude that histological examination of cadaveric lung tissue biopsies enables ascertainment or rule out of underlying pneumonia and prevents erroneous donor deferrals.