Lobar (croupous) pneumonia: old and new data.

Lobar pneumonia is a distinct clinico-pathological entity caused by S. pneumoniae, demonstrated by PCR testing and/or cytological examinations. Bacteriologic studies frequently give falsenegative results. Lobar pneumonia is characterized by three main histopathological patterns (congestion or microbeous edema, and red and gray hepatization) which usually occur side by side and not in chronological order. Early death is often related to heart failure and septic shock, while meningitis is a frequent complication later in the course.