Ultrastructural study of granulomatous tissue in tonsillar malakoplakia.

The ultrastructural study carried out in a case of tonsillar malakoplakia confirmed that granulomatous lesions consisted mainly of macrophages containing peculiar calcified inclusions (Michaelis-Gutmann bodies) considered pathognomonic for the disease. Moreover macrophages frequently contained ingested Gram-negative bacilli and presented aspects of mitochondrial degeneration and autophagy. These latter features were probably the consequence of bacterial infection rather than the expression of primary cellular defects, as the clinical evolution of this case of malakoplakia did not support the existence of generalized macrophage alterations.