- There are two etiologic agents. Identify and describe the manifestations of each, and name the probable organisms.
The more diffuse pulmonary involvement by the two organisms is due to cytomegalovirus (images 7.1 and 7.2), with numerous affected alveolar cells. The affected cells are markedly enlarged, have large nuclei with huge pink intranuclear inclusions surrounded by a halo. These inclusions occupy half the size of the nucleus. In some cells multiple smaller basophilic inclusions can be seen in they cytoplasm. These represent viral coat, or complete virions.
The second organism (images 7.3 and 7.4) is found focally in two or three areas showing necrosis surrounded by acute inflammatory cells and nuclear debris (images 7.3 and 7.4). Within these areas are starbursts of branching hyphae. These are evident even on H&E stain, but are highlighted by a GMS stain, where again the walls of the hyphae are stained black by the silver. The probably organism is Aspergillus, which can be seen in immunocompromised hosts. Other possibilities include Candida, which has pseudohyphae and budding yeasts.
- Why might this patient have had significant bleeding into his lung?
Aspergillus is an angioinvasive organism, and causes vasculitis and necrosis of vessel walls. Necrosis results in holes, holes in vessel walls results in bleeding.
- What other organs might be involved by these organisms?
Although any organ may be affected, CMV infection is especially prominent in the lung, adrenal, brain, eye, and gastrointestinal tract.
The pulmonary route is the most common site of invasion of Aspergillus in immunocompromised hosts, though invasion through the GI tract can also occur. In disseminated aspergillosis virtually any site can be involved, but brain and kidney are the most common.
