Course Map: Tumor-like Lesions: Malakoplakia

Malakoplakia
Aggregates of eosinophilic macrophages (von Hansemann histiocytes) form nodules or plaques, usually multiple, in the lamina propria [34,67]. There are lymphocytes and plasma cells also present (Fig. 1), but most of the cells are large and pink-staining. A variable number of them contain within the cytoplasm the diagnostic Michaelis-Gutmann inclusions (Fig. 2). These are round 5-8 micron bodies, blue or gray in color. More fully developed inclusions may assume a targetoid or bull's-eye appearance (Fig. 3) which may be highlighted with iron or calcium stains (Fig. 4).
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	Figure 1: A low power view showing lymphocytes, plasma cells, and numerous eosinophilic histiocytes.
	Figure 2: Early inclusions are small blue or gray dots, each with a clear halo.
	Figure 3: This shows five or more larger, targetoid inclusions (arrows).
	Figure 4: The inclusions are highlighted with an iron stain (arrows).