Tinea Nigra: Clinical and Diagnostic Guidance

Area of Science:

• Dermatology
• Mycology
• Infectious Diseases

Background:

• Tinea nigra is a rare superficial fungal infection.
• Characterized by asymptomatic, unilateral, brown to black macules on palms/soles.
• Diagnosis can be challenging due to rarity and resemblance to other pigmented lesions.

Observation:

• A 64-year-old woman presented with a three-month history of a slowly growing, asymptomatic dark spot on her left palm.
• The lesion was non-scaling and non-palpable.
• KOH preparation of palmar skin scrapings revealed pigmented yeast and hyphae.

Findings:

• Diagnosis of tinea nigra confirmed via microscopy and cultivation of *Hortaea werneckii*.
• Successful treatment with topical ketoconazole resulted in complete lesion resolution within one month.
• A diagnostic algorithm and treatment recommendations are proposed.

Implications:

• Highlights the importance of considering tinea nigra in the differential diagnosis of acral pigmented lesions.
• Emphasizes the need for increased awareness and accurate diagnosis, especially in non-endemic regions.
• Proposed algorithm and treatment protocols can aid healthcare professionals in managing this uncommon infection.