What fungi cause tinea versicolor?

Tinea Versicolor is Caused by Malassezia Species Fungi

Tinea versicolor is caused by an overgrowth of Malassezia species fungi, primarily M. globosa, M. furfur, and M. sympodialis. 1, 2 These lipophilic yeasts are part of the normal skin flora but can cause superficial infection under certain conditions.

Causative Organisms

• Primary causative organisms:

  • Malassezia furfur (previously known as Pityrosporum orbiculare) 3, 2
  • Malassezia globosa 2
  • Malassezia sympodialis 2

• Microscopic appearance:

  • Characteristic "spaghetti and meatballs" pattern with short, stubby hyphae intermixed with clusters of spores 1, 2
  • Dimorphic fungus appearing in both hyphal and yeast forms 4

Clinical Presentation

Tinea versicolor presents as:

• Hypopigmented or hyperpigmented macules/patches with fine scale 1, 2
• Primarily located on upper trunk, neck, and upper arms 2
• In dark-skinned individuals, predominantly hypopigmented lesions 4

Diagnosis

The diagnosis is typically made by:

1. Clinical appearance of characteristic lesions
2. Direct microscopy with KOH preparation showing short, stubby hyphae with clusters of spores 1, 2
3. Wood's lamp examination may show yellow-orange fluorescence in some cases

Treatment Considerations

Topical Therapy (First-line)

• Ketoconazole 2% cream applied once daily for two weeks 1, 3
• Other effective topical agents include selenium sulfide and terbinafine 5

Systemic Therapy (For extensive disease or treatment failures)

• Oral azole antifungals (fluconazole, itraconazole) 1, 2, 5
• Oral terbinafine is not effective for tinea versicolor 5

Important Clinical Pearls

• Recurrence is common due to Malassezia being part of normal skin flora 2, 5
• Repigmentation may take months even after successful treatment 1
• Prophylactic therapy should be considered for patients with frequent recurrences 1, 2
• Histopathology of affected skin in dark-skinned individuals shows thicker stratum corneum, more tonofilaments in the granulosum, and more sequestered melanosomes 4

Differential Diagnosis

• Confluent and reticulated papillomatosis
• Seborrheic dermatitis
• Pityriasis rosea
• Pityriasis alba
• Vitiligo 4

Understanding the causative organisms and their characteristics is essential for accurate diagnosis and effective management of tinea versicolor, particularly given its high recurrence rate and variable clinical presentation across different skin types.