How are birthmarks formed? Nevus of Ota, also known as blue-gray nevus, is commonly found on the face. Historically, it was referred to by the unflattering term "yin-yang face," causing significant distress. So how exactly does Nevus of Ota form? Let's explore below.
Clinical research by experts suggests Nevus of Ota may result from autosomal dominant inheritance, though this theory remains unconfirmed and contested by many scholars. However, clinical observations indicate a high hereditary component, accounting for approximately 50% of cases.
Medically defined as a pigmented birthmark characterized by blue-brown macules around the eyes, Nevus of Ota was first formally described by Ota in 1938. It essentially represents increased melanin in the dermis, often aligning with the distribution of peripheral branches of the trigeminal nerve.
Nevus of Ota
Lesions typically occur in areas innervated by the first and second branches of the trigeminal nerve, while Nevus of Ito appears in regions supplied by the posterior supraclavicular and lateral brachial nerves. This neural distribution pattern suggests melanocytes may originate from local neural tissue.
Nevus of Ota arises when melanocytes or their precursors become trapped locally during migration toward the epidermis. Melanocytes are typically located in the mid-dermis, though they may extend into the upper dermis or subcutaneous tissue. Numerous melanocytes, more concentrated in elevated areas of the lesion, exhibit elongated, spindle-shaped bodies scattered among dermal collagen fibers.Melanophages are occasionally observed in some lesions. When the lesion involves the eye, melanocyte infiltration may extend beyond the skin to deeper tissues, including the periosteum.
The exact cause of Nevus of Ota remains unclear. However, recent advancements in laser technology have provided a safe and effective treatment option. Laser therapy utilizes selective photothermolysis to eliminate Nevus of Ota without scarring or damaging surrounding healthy skin tissue, representing the most advanced approach currently available.