Enlarging pigmented patches on the hand

Area of Science:

• Dermatology
• Mycology
• Infectious Diseases

Background:

• Tinea nigra is a superficial fungal infection characterized by superficial, asymptomatic, pigmented macules.
• It is caused by dematiaceous fungi, primarily Hortaea werneckii.
• The infection is more prevalent in tropical and subtropical regions.

Observation:

• This case highlights the clinical presentation and pathological findings of Tinea nigra.
• The characteristic features include well-demarcated, irregular, brown to black macules on the palms and soles.
• Differential diagnosis is crucial, especially in endemic areas, to distinguish from other causes of palmoplantar hyperpigmentation.

Findings:

• Potassium hydroxide (KOH) preparation of skin scrapings is a rapid and effective method for diagnosing Tinea nigra.
• Microscopic examination reveals characteristic branching, septate, dark-walled hyphae.
• Histopathological examination confirms the presence of fungal elements within the stratum corneum.

Implications:

• Increased awareness of Tinea nigra's features can improve diagnostic accuracy among clinicians.
• Prompt diagnosis facilitates appropriate antifungal treatment and prevents misdiagnosis of other conditions.
• Understanding the endemic nature of the infection is vital for public health awareness and management strategies.