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.
Post-inflammatory hyperpigmentation (PIH). Post-inflammatory hyperpigmentation (PIH) causes skin darkening and discoloration that show up as spots, or as large patches on a person's body. This is because cells that normally produce brown pigment evenly across your skin go into overdrive and produce too much melanin.f the excess melanin is produced in the upper layer of skin (epidermis), the pigmentation color is a darker shade of brown. If the excess melanin is produced in the lower layer of skin (the dermis), a gray or blue discoloration becomes visible. post inflammatory hyperpigmentation. secondary to laser.