MICROSCOPIC FINDINGS (LUNG):
Hematoxylin & eosin (H&E) stains of lung sections from all lobes of the lung showed severe, diffuse hemorrhage. There was moderate to severe diffuse interstitial fibrosis, and some focal areas of necrosis. Some alveoli were filled with fibrin, inflammatory cells, and red blood cells, with evidence of acute and organizing alveolar damage. There was moderate to severe diffuse interstitial fibrosis. Although some small sized vessels showed severe narrowing of the lumen and thickening of the vessel wall, there was no evidence of acute vasculitis. A few sections show isolated Gram-positive cocci and diplococci, consistent with culture diagnosis of enterococcal sepsis. However, there were numerous lung sections that showed aggregates of long, thin branching rods approximately 2 micrometers in diameter (H&E magnification 10X, 40X, and 60X).
These branching rods stained negatively with a Grocott stain for fungus.
A Gram stain suggested these branching rods were Gram negative (Gram magnification 40X, 60X, 100X):
A standard Acid-Fast stain demonstrated these organisms were non-acid-fast (Acid Fast magnification 40X, 60X, 100X):
However, a modified acid-fast stain (the Fite-Faraco Modified Acid Fast stain) demonstrated these filamentous organisms to be primarily modified-acid-fast negative (Fite-Faraco MAF magnification 20X, 40X, 60X).
However, occasional areas demonstrated questionable (i.e. purple instead of red) modified-acid-fast positivity (Fite-Faraco MAF magnification 100X):