Cytologic diagnosis of extravesical malacoplakia

Area of Science:

• Pathology
• Immunology
• Microbiology

Background:

• Malacoplakia is a rare chronic granulomatous inflammation.
• It most commonly affects the urinary tract in middle-aged women.
• It involves an atypical inflammatory response to bacterial infections, often *Escherichia coli*, suggesting host immune dysfunction.

Observation:

• Two distinct cases of malacoplakia are presented.
• One case involved the vagina, and the other affected the perianal subcutaneous tissue and lung.
• Diagnosis was achieved concurrently using both cytology and histological examination of tissue sections.

Findings:

• Characteristic von Hansemann histiocytes were observed, larger than alveolar macrophages.
• These cells displayed granular cytoplasm due to lysosomal accumulation.
• Mineralization of lysosomal bodies led to the formation of pathognomonic Michaelis-Gutmann bodies, distinguishable from psammoma bodies and yeasts.

Implications:

• The concurrent use of cytology and histology aids in accurate malacoplakia diagnosis.
• Prompt diagnosis facilitates effective therapy and complete disease resolution.
• Understanding the cellular pathology, including Michaelis-Gutmann bodies, is crucial for differentiating malacoplakia from other conditions.