This is a granuloma from a mediastinal lymph node from a person who died in Kansas City. These are usually due to histoplasmosis.
This granuloma exhibits ovoid nuclei surrounded by a palely-eosinophilic cytoplasm. Giant cell formation is usually seen in granulomas although there are no really good ones here.
This infection is common in the midwest and is acquired primarly by inhalation of starling bird droppings that containg spores. Histoplasmosis is an opportunistic infection and hence patients with AIDS are at a high risk. Histoplasma capsulatum is easy to recognize under the microscope, because it is a 2 micron yeast.
Can you find any histoplasmosis organisms in the picture? For help, click here.
If there is a need, the diagnosis may be confirmed by culture of the organism.