Among the many spots, there is one that was once not taken seriously and often confused with other pigmentation, even leading to some unnecessary misunderstandings. Today, I would like to talk about the brown bruise on the cheek. Zygomatic brownish cyanosis was previously thought to be a disease similar to nevus of Ota, so it was also known as acquired nevus of Ota or Horis spots. With the in-depth research, scholars found that zygomatic brown bruise is an independent disease, and its onset age is mostly between 25-35 years old, and its pathogenesis is not fully understood. Characteristics of brownish-blue spots: brownish-blue spots on the zygomatic area are mainly round, scattered and non-fused spots, and their color is mainly grayish-blue (or blue-black), while others can be brown. It is symmetrically distributed in the temporal area, zygomatic area and eyelids bilaterally, and in a few people, it is also distributed in the frontal area. Histopathological HE staining showed scattered, small number of spindle-shaped pigment-containing cells in the superficial dermis, positive expression of HMB45, and electron microscopic identification as nevus cells. These indicate that brown bruise is a pigmented nevus (so also called zygomatic brown bruise nevus) with small size and small number of melanin vesicles, which is different from both nevus of Ota and melasma. Studies have shown that there is a genetic susceptibility to this disease. In the dermis, there are congenital dormant or inactive pigment cells (c-KIT and or complexine kinase-related protein 2 positive), and when stimulated by some non-specific factors later, the skin cells undergo an inflammatory immune response, and the secreted endothelin-1 or granulocyte colony-stimulating factor causes the activation of dormant pigment cells. The pigment synthesis increases and the pigmentation becomes visible. There are various factors that trigger the activation of dormant pigment cells: ultraviolet radiation (sun exposure), cosmetics, sex hormone fluctuations, chronic inflammation, etc. This suggests that laser, phototherapy and cosmetics may also induce the appearance of brown spots on the cheek area. Although the incidence of such cases is very low, it should be explained to patients before treatment, otherwise, once induced, it is often difficult to explain and misunderstood as caused by improper treatment, and disputes are easily formed. Treatment of brown spots At present, the main treatment method is to apply Q-modulated laser for treatment, which can generally be cured. Of course, laser treatment also has the risk of hyperpigmentation or depigmentation. Tip: Whitening agents, superficial or moderate chemical peeling agents are not effective for brown bruises. Differential diagnosis of brown bruise 1. Nevus of Ota: The onset of the disease is often at birth or shortly after birth (individual can develop in adolescence or even in the twenties). The color is mainly grayish-blue (or blue-black), and a few of them are also coffee-colored. Generally, they are distributed on cheek, temporal and forehead areas, and in some severe cases, on cheeks. 2.Chloasma: It is common in middle-aged women aged 30-45 years old, with single occurrence at the beginning, and then usually fused into patches with brown color. The cheek area is also a good site, and the cheek area and forehead area are also more common, and in serious cases, the whole area can be seen and fused into patches.