Thyroid & parathyroid
Other thyroid nonneoplastic
Malakoplakia
Author: Andrey Bychkov, M.D., Ph.D.
Last author update: 1 March 2015
Last staff update: 11 July 2023
Copyright: 2015-2024, PathologyOutlines.com, Inc.
PubMed Search: malakoplakia thyroid
Table of Contents
Definition / general | Terminology | Epidemiology | Clinical features | Radiology description | Case reports | Treatment | Gross description | Microscopic (histologic) description | Microscopic (histologic) images | Cytology description | Positive stains | Electron microscopy description | Differential diagnosis | Additional referencesCite this page: Bychkov A. Malakoplakia. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/thyroidmalakoplakia.html. Accessed December 4th, 2024.
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)
Terminology
- Malakoplakia (or malacoplakia) = Greek "malakos" (soft) + "plakos" (plaque)
Epidemiology
- < 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
- 50, 54 and 60 year old women (Am J Clin Pathol 1989;92:813, Int J Surg Pathol 2015;23:308, Acta Cytol 1996;40:970)
- 64 year old woman with malacoplakia manifesting as a chronic inflammatory mass (Ear Nose Throat J 2003;82:876)
- 72 year old woman with thyroid gland malakoplakia with autoimmune thyroiditis (Histopathology 1993;23:491)
Treatment
- 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
Michaelis-Gutmann
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
- Inclusions: calcium (von Kossa), iron (Prussian blue), PAS+ diastase resistant
- CD68 for macrophages contained inclusions
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
Additional references
