[Histological diagnosis of lung bacterial necrotizing infections: a study of four fulminant cases].

We report the clinical and histopathological features of four cases of pulmonary bacterial infections associated with extensive necrosis, which were fatal within a few hours (two cases of group A Streptococcus, one case of Staphyloccocus aureus and one case of Haemophilus influenzae infection). These bacterial infections are extremely severe conditions due to the production of necrotizing toxins. Histological findings are distinctive, showing extensive hemorrhagic necrosis, widespread layers of bacteria, and very few or no inflammatory cell components. These dramatic infections are extremely rare, occuring with no apparent underlying disease, both in immunodeficient and immunocompetent patients. The main differential diagnosis is a viral infection, difficult to diagnose on histological examination alone. The diagnosis is based on histological and microbiological results.