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PubMed search: malakoplakia [title] pulmonary

Elliot Weisenberg, M.D.
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Cite this page: Weisenberg E. Malakoplakia. website. Accessed April 2nd, 2023.
Definition / general
  • Usually in urinary tract; very rare in lung, usually in immunocompromised patients
  • Caused by macrophage dysfunction involving intracellular lysosomal mediated killing of bacteria
  • In AIDS patients, usually due to Rhodococcus equi, an animal pathogen causing opportunistic infections (Chest 1999;115:889)
Case reports
  • Antibiotics
Gross description
  • Nodular masses or infiltrates with cavitation
Gross images

Images hosted on other servers:
Grayish white, ill<br>defined lesion with<br>central cavitation

Grayish white, ill
defined lesion with
central cavitation

Microscopic (histologic) description
  • Intraalveolar histiocytes with pink or foamy cytoplasm (von Hansemann’s histiocytes) that fill and destroy alveoli, not interstitium
  • Histiocytes contain PAS+ bacteria, also Michaelis-Gutmann bodies (round / oval structures, usually intracellular, 5 - 20 microns, with laminated or targetoid appearance that stain deeply with H&E, iron and calcium stains)
  • Also lymphocytes, plasma cells and neutrophils
Microscopic (histologic) images

Images hosted on other servers:
Various images Various images

Various images

Differential diagnosis
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