A value of NULL indicates that the value is unknown. A value of NULL is different from an empty or zero value. No two null values are equal. Comparisons between two null values, or between a NULL and any other value, return unknown because the value of each NULL is unknown.
Skin Spots on the Face. Most causes of spots on face are harmless. They can be a variety of colors including white, red, black or brown. Common causes include cumulative sun exposure, acne, and skin tags. Keratoacanthoma (hyperkeratosis) is a lesion that grows rapidly, usually on areas exposed to the sun.
Excessive sun exposure may cause the development of porokeratosis. Porokeratosis is a common skin condition. Exposure to artificial UV light, such as the type used in tanning beds, correlates with porokeratosis. As porokeratosis spreads, a person may start to experience fever and fatigue.It's important for porokeratosis patients to wear sunscreen while outdoors, regardless of the weather.t is possible to have a single lesion or multiple abnormal spots on the body. Lesions typically do not change in size and shape over time, and any changes that do occur can be signs of developing skin cancer. Skin carcinomas that arise due to porokeratosis are usually characterized by hard, scaly, dark-colored lesions.