Cutaneous malakoplakia in pigs inoculated with Rhodococcus equi

Cutaneous malakoplakia was observed in pigs inoculated intramuscularly with Rhodococcus equi strains of intermediate virulence. Macroscopically, the i noculation sites showed the indurated swelling of the skin. Histopathologic ally, abscess formation with histiocytic granulomatous reaction was observe d, Many macrophages contained target or owl-eye shaped hematoxyphil intracy toplasmic inclusions or calcosherites (Michaelis-Gutmann bodies) of various sizes. The Michaelis-Gutmann bodies were also seen outside of the macropha ges. Histochemically, most Michaelis-Gutmann bodies stained positively with the von Kossa silver method and periodic acid Schiff. Immunohistochemicall y, some of Michaelis-Gutmann bodies were stained by two rabbit polyclonal a ntibodies (rabbit anti-A5 serum and rabbit anti-ATCC 33701 serum) and a mou se monoclonal antibody (anti-20-kDa antigen monoclonal antibody). This is t he first report of cutaneous malakoplakia in domestic animals, which also r evealed the relationship between R equi infection and malakoplakia immunohi stochemically. This experimental swine model is useful to investigate the m orphogenesis of Michaelis-Gutmann bodies in malakoplakia through chronologi cal skin biopsies. (C) 1998 Federation of European Microbiological Societie s. Published by Elsevier Science B.V. All rights reserved.