Thyroid & parathyroid

Other thyroid nonneoplastic


Topic Completed: 1 March 2015

Minor changes: 21 September 2020

Copyright: 2015-2021,, Inc.

PubMed Search: malakoplakia thyroid

Andrey Bychkov, M.D., Ph.D.
Page views in 2020: 431
Page views in 2021 to date: 372
Cite this page: Bychkov A. Malakoplakia. website. Accessed December 3rd, 2021.
Definition / general
  • Rare chronic inflammatory / granulomatous disease that most commonly affects genitourinary tract (see topics in Bladder, Kidney, Prostate, Testis chapters)
  • Usually in immunocompromised adult women due to inadequate phagocytosis / degradation of gram negative bacteria by macrophages
  • Microscopic hallmarks are Hansemann cells and Michaelis-Gutmann bodies (see "Micro description" below)
  • Malakoplakia (or malacoplakia) = Greek "malakos" (soft) + "plakos" (plaque)
  • < 10 cases of thyroid involvement have been reported, all in women (see below)
Clinical features
  • Difficulty swallowing, fever, asymmetrical enlargement of the gland and destruction of surrounding tissues (nonspecific)
  • Diagnosis only after surgical excision
Radiology description
  • Ultrasound: solid nodule
  • I-131 scan: low uptake
Case reports
  • Antibiotics (quinolones, rifampicin and trimethoprim-sulfamethoxazole)
  • Mass excision
Gross description
  • Unencapsulated nodule several cm in diameter, yellow to white, usually soft
Microscopic (histologic) description
  • Sheets of histiocytes with eosinophilic granular cytoplasm containing characteristic basophilic or PAS+ diastase resistant inclusions / bodies loaded with calcium, iron and bacterial debris (Hanseman cells)
  • Michaelis-Gutmann bodies (calcospherites) are round laminated mineralized concretions, 1 - 10 microns, intra- or extracellular; may be targetoid, with a dense central crystalline core
  • Inflammatory (neutrophils, plasma cells, lymphocytes and granulation tissue) to fibrotic background
Microscopic (histologic) images

Images hosted on other servers:

Malakoplakia (arrows at Michaelis-Gutmann bodies), bladder

bodies; von Kossa
calcium stain

Cytology description
  • Numerous histiocytes with abundant eosinophilic granular cytoplasm containing basophilic inclusions (4 - 10 microns) consistent with Michaelis-Gutmann bodies (Acta Cytol 1996;40:970)
  • The background contains similar round basophilic bodies, blood and inflammatory cells (Int J Surg Pathol 2015;23:308)
Positive stains
Electron microscopy description
  • Macrophages with numerous phagolysosomes packed with undigested bacteria
  • Concentric crystalline laminations with dense inner zone containing calcium salts crystals and thin outer zone of amorphous granular material (Histopathology 1993;23:491)
Differential diagnosis
  • Malignancy of thyroid or neck organs
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