Tinea versicolor

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Tinea versicolor

• Diagnosis also based upon characteristic clinical
  presentation
• Rapid and easy way to confirm the diagnosis is by
  using a Wood's lamp. Yellow to yellow-green
  fluorescence is characteristic of fine scales
  taken from active lesions. Although the
  sensitivity of this procedure is reduced when
  patients have taken a recent shower

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Woods lamp longwave UV light used in dark room
will cause Tinea microbes to fluoresce. This
image is of an affected scalp.
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Tinea versicolor

• Recent data implicates these microbes, combined
  with multifactorial host factors (genetic
  predisposition env. factors such as emotion,
  changes in skin pH or sebum saturation) as the
  direct cause of seborrhoeic dermatitis, with
  dandruff being the mildest manifestation

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Tinea nigra

• Etiology
• Phaeoannelomyces werneckii (synonyms Hortaea
  werneckii (current name) or Exophalia werneckii),
  a common saprophytic fungus believed to occur in
  soil, compost, humus and on wood in humid
  tropical and sub-tropical regions
• Epidemiology
• Occurs in warm moist climates
• World-wide distribution - most common in tropical
  regions of Central and South America, and the
  Caribbean Islands, but also seen in Africa,
  South-East Asia and Australia

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Tinea nigra

• Clinical manifestations
• Asymptomatic in most cases. When symptomatic
  causes brownish black discoloration primarily on
  the palms of the hands, and often includes
  pruritis. Lesions resemble AgNO3 stains.
  Lesions are non-inflammatory and non-scaling.

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Tinea nigra
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Tinea nigra

• Laboratory diagnosis
• KOH preparation performed on skin scrapings
• Microscopic findings include
• Short septate hyphae
• Two celled yeast cells producing anneloconidia
  septate buds that leave ring scars after conidial
  separation

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Tinea nigra KOH
Septate Hyphae
Septate two-cell Yeast
Yeast cells are anneloconidia microscopic rings
remain after separation
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Tinea nigra

• Laboratory diagnosis
• When cultured on SDA P. werneckii grows in
  2-3 weeks as a dark colored (dematiaceous) moist
  shining yeast
• Older cultures of Phaeoannelomyces werneckii
  become velvety moulds

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Phaeoannelomyces werneckii