Differential Diagnosis for Scaly Hypopigmented Macular Lesions that Fluoresce Under Woods Lamp
- Single Most Likely Diagnosis
- Pityriasis versicolor: This condition is characterized by scaly, hypopigmented or hyperpigmented macules that typically fluoresce under Wood's lamp due to the presence of Malassezia yeast. It's a common skin condition, especially in young adults, and the description closely matches its clinical presentation.
- Other Likely Diagnoses
- Vitiligo: Although vitiligo typically presents with non-scaly, depigmented patches, some forms can have a fine scale and may show a blue-white fluorescence under Wood's lamp. It's an autoimmune condition leading to loss of melanocytes.
- Pityriasis alba: This is a mild, chronic, eczematous condition seen mainly in children, characterized by round or oval, faintly erythematous, scaly patches that may appear hypopigmented. It might show some fluorescence under Wood's lamp, though it's not a hallmark.
- Do Not Miss Diagnoses
- Tinea versicolor due to other fungi: While Malassezia is the most common cause, other fungi can cause similar lesions. Missing a treatable fungal infection could lead to unnecessary suffering and potential for spread or secondary infection.
- Sarcoidosis: Though less common, sarcoidosis can present with skin lesions that might appear hypopigmented and could potentially fluoresce under certain conditions. It's a systemic disease that can affect multiple organs, making early diagnosis critical.
- Rare Diagnoses
- Idiopathic guttate hypomelanosis: This condition presents with small, discrete, hypopigmented macules, often on the extremities. While it doesn't typically fluoresce under Wood's lamp, it's a consideration in the differential for hypopigmented lesions.
- Leprosy (Hansen's disease): In its early stages, leprosy can cause hypopigmented skin lesions. Though rare in many parts of the world, it's a critical diagnosis not to miss due to its potential for serious neurological and dermatological complications if left untreated.