Skin-nontumor
Infectious disorders
Malakoplakia

Author: Abha Soni, D.O., M.P.H. (see Authors page)
Editor: Andrzej Slominski, M.D., Ph.D.

Revised: 21 March 2016, last major update March 2016

Copyright: (c) 2003-2016, PathologyOutlines.com, Inc.

PubMed Search: Malakoplakia [title] skin
Cite this page: Malakoplakia. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/skinnontumormalakoplakia.html. Accessed December 8th, 2016.
Definition / General
  • Greek derivation: Malako-soft and Plako-plaque
  • Chronic granulomatous inflammation
  • Most commonly occurs in the genitourinary tract
  • Rarely occurs in skin (<100 cases reported, Arch Pathol Lab Med 2008;132:113)
  • Co-involvement of the gastrointestinal tract and other visceral organs also rarely occurs
Terminology
Etiology
  • Likely due to inadequate killing of bacteria by macrophages or monocytes that exhibit defective phagolysosomal activity (eMedicine - Malakoplakia)
  • Partially digested bacteria accumulate in monocytes or macrophages, leading to deposition of calcium and iron on residual bacterial glycolipid
  • Basophilic inclusion structure that contains calcium is called Michaelis-Gutmann body, and is considered pathognomonic
  • Patients typically suffer from immunosuppression (HIV, cancer, lymphoma, post-transplant) or autoimmune diseases (SLE, rheumatoid arthritis)
  • Most cases are associated with E.coli
Clinical Features
  • 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 firm nodules up to 2 cm in diameter
  • Skin colored, yellow or pink
  • May contain a central dimple or draining sinus
Diagnosis
  • Histologic diagnosis required
Case Reports
Treatment
  • Antibiotics that concentrate in macrophages (quinolones, trimethoprim-sulfamethoxazole) are associated with a high cure rate
  • Antibiotic therapy against E. coli with surgery is most effective
Clinical Images

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Purple plaque

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After treatment

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

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Michaelis-Gutmann body

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Calcified structures

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Periodic acid Schiff stain

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PAS, Von Kossa, Prussian blue

Positive Stains
Electron Microscopy Description
  • Histiocytes containing phagolysosomes with intact or partially digested bacteria
  • The granules within the macrophages, which stain with PAS, contain engorged lysosomes that contain bacteria debris