A 42-year-old Asian woman presents with bilateral, speckled, slate-grey to blue-brown macules over both malar prominences present for several years. Wood's lamp examination shows no enhancement of the pigmentation. She has failed multiple topical depigmenting regimens. What is the most likely diagnosis?
- A Hori's naevus (acquired bilateral naevus of Ota-like macules) ✓
- B Epidermal melasma
- C Freckles (ephelides)
- D Post-inflammatory hyperpigmentation
Correct answer: A. Hori's naevus (acquired bilateral naevus of Ota-like macules)
Explanation
Hori's naevus consists of acquired bilateral dermal melanocytosis in middle-aged Asian women, appearing as speckled slate-grey malar macules. Because the melanocytes lie in the dermis, Wood's lamp shows no enhancement and topical agents fail; the definitive treatment is Q-switched Nd:YAG laser targeting dermal pigment. Epidermal melasma enhances with Wood's lamp and responds to topicals, while freckles are smaller, lighter, and sun-dependent.
Reference: Fitzpatrick's Dermatology, 9th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.