GPR: 2021 - Week 16

From MGH Learn Pathology

Clinical history

52 year old male s/p renal transplant on immunosuppressive therapy presents with an indurated lesion on his left arm cultures were taken and the growth on Sabouraud agar is shown below.


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Aspergillus niger
  • Characteristic early yellow to white color which later turns black
  • reverse is a creamy white
  • filamentous fungi that tend to form hyphae
  • uniquely form dark brown/black pigment in conidial heads
  • Can be found in mycetoma and otomycosis



Alternaria spp.

  • Dematiaceous fungi with over 50 different species
  • Alternaria alternata is the most common isolate in humans
  • Opportunistic pathogen especially in immunocompromised hosts
  • Dark brown/ black color acquired via melanin



Scedosporium boydii

  • Aka Pseudallescheria boydii
  • another dematiaceous fungi
  • Greyish-white colony with grey-dark grey reverse
  • fast growing
  • while growing in humans the fungi often lack pigment making diagnosis difficult

Dr. Branda

This week's Gross Pathology Roundup was presented by Leif Timothy Helland, MD on Mon, Apr 19, 2021.