Microscopic examination demonstrates the characteristic thick-walled spherical or oval yeast forms and coarse septate mycelium, often broken up into short filaments. This combination of mycelium strands and numerous spores is commonly referred to as "spaghetti and meatballs."
Liquid blue ink, methylene blue, or Swartz-Medrik stain can be added to the KOH preparation for better visualization of the causative organism.
Scales may also be removed using clear adhesive tape; they are then directly examined. The tape must be clear and is pressed several times over involved areas of skin. The tape is then lightly pressed, sticky side down, onto a microscope slide. A small drop of methylene blue or other appropriate stain is placed at the edge of the tape and allowed to run between the tape and the glass slide. Spores, often in grapelike clumps, and mycelium are easily seen. See the image below.
Clear adhesive tape can be pressed onto areas of tinea versicolor to collect hyphae and spores. The tape is then lightly pressed onto a glass slide, and a drop of methylene blue is placed at the edge of the tape. The methylene blue is allowed to run under the tape staining Malassezia furfur. The spores and hyphae easily are seen against a background clutter of keratinocytes and glue.
A few reports in literature have recently stated that 1% Chicago Sky Blue 6B (CSB) staining with 10% KOH is a new promising contrast diagnostic method for pityriasis versicolor, with 100% of sensitivity compared with 60.9% in culture. [7]
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In patients with lighter skin color, lesions frequently are a light tan or salmon color.
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Upon potassium hydroxide (KOH) examination, hyphae are visible and grow into strands within clumps of keratinocytes. Thick-walled spores frequently occur in grapelike clumps. Individual spores and short stubby hyphae float in the clear areas between clumps of keratinocytes. Many of the short hyphae are dystrophic.
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Scale is frequently difficult to appreciate upon clinical examination.
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This individual developed skin discoloration and mild itching every summer for the past few years. These patients should be instructed on the prophylactic use of topical therapy.
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This superficial plaque of tinea versicolor is located in the right antecubital fossa of an adult. This appearance and distribution is uncommon but not rare. A potassium hydroxide (KOH) preparation confirmed the diagnosis.
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Although tinea versicolor is uncommon in children in temperate climates, when it does occur, it is more likely to be atypical in distribution. This 7-year-old boy had areas of tinea versicolor across the forehead and both temples. He was in good health and lived in Washington state when he was diagnosed.
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In some patients, the areas affected by tinea versicolor are not always obvious. In this patient, the abnormal areas are hypopigmented.
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Clear adhesive tape can be pressed onto areas of tinea versicolor to collect hyphae and spores. The tape is then lightly pressed onto a glass slide, and a drop of methylene blue is placed at the edge of the tape. The methylene blue is allowed to run under the tape staining Malassezia furfur. The spores and hyphae easily are seen against a background clutter of keratinocytes and glue.
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Some patients present with extensive tinea versicolor. This patient related that his discoloration had been present for more than 20 years. The light-colored areas on the abdomen are the normal areas of skin. Although topical therapy alone is usually effective, this patient may benefit from initial therapy with oral ketoconazole, followed by selenium sulfide applications in the shower 2-3 times a month.
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Significant hyperpigmentation caused by a tinea versicolor infection.
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Confluent and reticulated Gougerot and Carteaud papillomatosis.
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Mycelium strands and numerous spores observed on a potassium hydroxide (KOH) preparation of tinea versicolor. This combination is commonly referred to as "spaghetti and meatballs."
