Histoplasma capsulatum

Histoplasma capsulatum

These are oval-spherical in shape with a clear halo (that’s the capsule) invading neutrophils. There is also a sneaky nucleated red cell.

Pseudohyphae +/- budding can also be seen from the cells (use Gomori’s methenamine silver stain to highlight them)

Blastomyces dermatitidis and Cryptococcus neoformans looks similar

Also look for:

  • Haemophagocytosis
  • Increased plasma cells
  • Granulomas 
  • STAINS: PAS+ and Prussian blue reaction +

If your patient has this, they are immunocompromised and therefore check HIV and the clinical details (e.g. immunosuppressive medication, primary immunodeficiency)

Image credit: www.photomacrography.net

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