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Skin-nontumor / Clinical Dermatology

Infectious disorders

Malakoplakia


Reviewer: Mowafak Hamodat MB.CH.B, MSc., FRCPC, Eastern Health, St. Johns (Canada) (see Reviewers page)
Revised: 21 December 2010, last major update December 2010
Copyright: (c) 2002-2010, PathologyOutlines.com, Inc.

Definition
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● Persistent lesions that rarely occur in skin (<100 cases reported, Arch Pathol Lab Med 2008;132:113)

Etiology
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● Likely due to inadequate killing of bacteria by macrophages or monocytes that exhibit defective phagolysosomal activity (eMedicine)
● Partially digested bacteria accumulate in monocytes or macrophages, leading to deposition of calcium and iron on residual bacterial glycolipid
● Basophilic inclusion structure is called Michaelis-Gutmann body, and considered pathognomonic
● Patients typically have immunosuppression (HIV, cancer, lymphoma, post-transplant) or autoimmune disease (SLE, rheumatoid arthritis)

Clinical features
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● Most often affects the urinary tract, but may affect GI tract, lymph nodes, brain, bone, adrenals and skin
● May present with papules, plaques, polyps, ulcers and sinuses
● Skin lesions are non progressive but persistent

Case reports
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● 23 year old immunocompetent Syrian man with perianal disease (Dermatol Online J 2010;16:10)

Micro description
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● Confluent sheets of histiocytes (von Hanseman cells ) with eosinophilic granular cytoplasm and eccentric nuceli
● Cells contain characteristic basophilic bodies containing calcium (von Kossa+)
● Round, sometimes laminated structures are known as Michalelis Gutmann bodies
● The targetoid pattern is accentuated by staining with PAS
● Also histiocytes, neutrophils, plasma cells, lymphocytes and granulation tissue

Micro description
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Perianal disease

Michaelis-Gutmann body

Positive stains
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● PAS, Pearl's (iron) stain and von Kossa (calcium)
● Microorganisms may stain with anti-bCG antibodies (J Am Acad Dermatol 2000;43;351)

Electron microscopy
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● Histiocytes containing phagolysosomes with intact or partially digested bacteria

End of Skin-nontumor / Clinical Dermatology > Infectious disorders > Malakoplakia


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