Tinea nigra in Adult
After contamination from an infected source (eg, soil, sand, waste, or wood), the mycosis infects the stratum corneum, resulting in a dark macule or patch as the fungal hyphae produce melanin. The incubation period is typically 10-15 days.
The most frequently affected populations are children and adolescents (children are more prone to exposure to the fungus); however, persons of any age may be affected.
Immunocompromised Patient Considerations
The fungus involved in causing infections of tinea nigra can lead to serious infections in immunocompromised patients. There is a risk of disseminated disease from superficial cutaneous fungal infections noted in transplant patients.
B36.1 – Tinea nigra
186289000 – Tinea nigra
Differential Diagnosis & Pitfalls
- Talon noir – Intracorneal hemorrhage, secondary to trauma.
- Acral melanocytic nevus – Presents with furrow or fibrillar pattern on dermoscopy, which is not seen in tinea nigra.
- Melanoma – Presents with irregular borders, color of different shades, expanding diameter; easily differentiated from tinea nigra using dermoscopy. No hyphae found on potassium hydroxide (KOH) scrapings.
- Postinflammatory hyperpigmentation – Sequelae of inflammatory skin condition; evidence of inflammatory condition prior to hyperpigmentation.
- Fixed drug eruption
- Acral nevi
- Postinflammatory hyperpigmentation
- Addison disease – Increased pigmentation resulting from increased levels of the pituitary hormones (melanocyte stimulating hormone [MSH] and adrenocorticotropic hormone [ACTH]) in Addison disease. Pigmentation usually occurs on the mucosa, elbows, knees, and dorsa rather than the plantar surface of hands.
- Vitamin B12 deficiency
- Laugier-Hunziker syndrome
- Secondary syphilis – Pink, red, violaceous, or brown macules or thin papules, smooth or scaly, may be tender on palpation. Other features of secondary syphilis may accompany palmoplantar manifestations.