A 20-year-old patient presents with a non-progressive hypopigmented lesion on the trunk. On Wood's lamp examination, there is white accentuation. Diascopy is negative. What is the most likely diagnosis?
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Non-progressive hypopigmented patch with negative diascopy suggests nevus depigmentosus.
Step 1: Understanding the Question:
The question asks to differentiate between several common hypopigmented lesions based on clinical history and examination findings.
Key features: "non-progressive", "white accentuation on Wood's lamp", and "negative diascopy". Step 2: Detailed Explanation:
Analyzing the findings:
Non-progressive: Suggests a stable, often congenital lesion rather than an acquired, spreading condition like Vitiligo.
Wood's Lamp White Accentuation: Indicates a significant loss of melanin. In vitiligo, the loss is total (depigmentation), leading to "bright blue-white" fluorescence. In nevus depigmentosus, there is a reduction in melanin (hypopigmentation), leading to "off-white" accentuation.
Diascopy Negative: This is a crucial test. In Nevus anemicus (C), the lesion disappears on diascopy because it is caused by localized vascular hypersensitivity, not pigment loss. A negative diascopy (lesion stays visible) rules out Nevus anemicus.
Evaluating the Diagnosis:
Nevus depigmentosus (B): Is a stable, non-progressive hypopigmented patch present from birth or early childhood. It shows off-white accentuation on Wood's lamp.
Vitiligo (A): Is usually progressive and acquired, though stable forms exist.
Step 3: Final Answer:
Based on the stability of the lesion and the negative diascopy, Nevus depigmentosus is the most likely clinical diagnosis.
