Case 73. Actinomycosis of lung (50 y-o F)

　 　 　 　
　 Surgical specimen of an irregular-shaped lung nodule in a previously healthy individual 　
　 　 　 　

　

 　 Formation of grains within the abscess cavity is pathognomonic of actinomycosis (HE, low power). If grains are not included in the specimen, the histopathological diagnosis may be inflammatory pseudotumor of the lung.